Management of stress in fish for sustainable aquaculture development

Full text

Researcher, 2011;3(4) http://www.sciencepub.net/researcher
http://www.sciencepub.net/researcher researcher135@gmail.com
28
Management of Stress in Fish for Sustainable Aquaculture Development
, Ugwemorubong Ujagwung Gabriel, Ojo Andrew Akinrotimi
1 Department of Fisheries and Aquatic Environment, Rivers State Univ. of Sc. and Tech.
PMB 5080 Port Harcourt, Nigeria
2. African Regional Aquaculture Centre/Nigerian Institute for Oceanography and Marine Research, P.M.B.
5122. Port Harcourt Nigeria.
ojoakinrotimi@yahoo.com, ugwemg@yahoo.com
Abstract :The estimated contribution of aquaculture to global supplies of fish has risen tremendously over the years.
This is due to the fact that aquacultural practice, all over the world is becoming more and more intensive; utilizing
available resources thereby enhancing maximum productivity. An inevitable part of intensive aquaculture is
manipulation of fish, which include handling, stocking, sorting, confinement, transportation and other farm
operations right from hatchery to the final commercial stage. However, these procedures produce disturbances which
elicit stress responses, leading to decreased performance, altered peripheral leucocytes distribution such as
heterophillia and lymphocytopenia, as well as increased susceptibility of fish to diseases, and in extreme cases leads,
to mortality. A sound and working knowledge of the importance of stress in aquaculture management and its
consequence in causing decline in yield, which will ultimately lead to loss in profit. This aspect of fishery
management must be adequately looks into. Hence, this paper review critically the causes, mechanisms of stress,
consequences and various ways of effectively alleviating it in aquacultural practice, so as to enhance the
sustainability of aquaculture as a major source of fish supply for the growing population in the world.
[Ugwemorubong Ujagwung Gabriel, Ojo Andrew Akinrotimi. Management of Stress in Fish for Sustainable
Aquaculture Development. Researcher. 2011;3(4):28-38]. (ISSN: 1553-9865). http://www.sciencepub.net.
Key words: stress, fish, management, aquaculture, sustainable yield
1. Introduction
Over the past decades aquaculture has
expanded, intensified, and diversified in response to an
increasing demand for fish as a source of protein
globally. This is because production from capture
fisheries has reached their maximum potential possible,
as the catch is dwindling with each passing day
(Akinrotimi et al 2007a). According to FAO (2006),
fish supplies from capture fisheries will, therefore, not
be able to meet the growing global demand for aquatic
food and protein. Hence there is the need for viable
alternative fish production systems that can sufficiently
meet this demand and aquaculture fits exactly into this
role (FAO, 2005; Akinrotimi et al., 2007a).
The estimated contribution of aquaculture to global
supplies of fish, crustaceans and mollusks increased
from 3.9% in 1970 to 27.3% in 2000 (FAO 2002).
From the year 2000 and beyond, aquaculture has grown
in leaps and bounds (Table 1) making it the fastest
growing food producing industry in the world
(NACA/FAO, 2000). Although rapid growth of
aquaculture in the past two decades has enabled the
world fisheries supply to keep pace with population
growth (Boyd et al. 1998; Savas, 1998), the future of
aquaculture still lies in increasing production
efficiencies and intensities, so as to produce more fish
using less land water and financial resources (Jamu and
Ayinla, 2003).
As aquaculture world over is becoming more and
more intensive, this involves manipulation of fish and
other farm management procedures which include
handling, liming confinement, fertilization,
transportation and other operations from the hatchery to
the final commercial stage (Angelids et al., 1987;
Gabriel et al., 2007a). According to Pickering (1981)
these management procedures as crucial as they are,
produce some level of disturbances, which can elicit a
stress response leading to decreased fish performance
(Maule and Shreck, 1990), alterations of the peripheral
leucocyte distribution, such as heterophilia and
lymphocytopaenia (Ellsaesser and Clem 1986,
Ainsworth et al., 1991; Gabriel et al. 2007a) increased
susceptibility to diseases (Pickering and Pottinger 1985;
Maule et al. 1989) and in extreme, cases leads to
mortality (Akinrotimi et al. 2007b). It should be noted
that a very devastating effect of stress or the stock may
occur during application of these management
procedures with and without apparent warning. This
then raises the question of proper monitoring of stress in
fish, in order to reduce to the barest minimum the
negative effects of such management procedures. This
paper critically reviews the causes, mechanisms and
consequences of stress in cultured fish and suggests
various ways such stresses can be effectively managed.

Researcher, 2011;3(4) http://www.sciencepub.net/researcher
http://www.sciencepub.net/researcher researcher135@gmail.com
29
2. Description of stress in fish
Stress is any condition that causes physical or
psychological discomfort which results in the release of
stress-related hormones or specific physiological
responses (Foster and Smith, 2007). Stoskopf (1993)
observes that stress is present virtually in the lives of all
living organisms and can be described as the latent force
that brings about physical, psychological and
physiological change and adjustment. Unfortunately the
term “stress” is used inconsistently. It is sometimes
taken to mean the environmental alteration (stressor)
itself and at other times the response of the fish,
population and ecosystem (Pickering, 1981). Selye
(1950) defined stress as “the sum of all the
physiological responses by which an animal tries to
maintain or re-establish a normal metabolism in the face
of physical and chemical force”. But this definition
according to Wedemeyer et al. (1990) does not consider
the fact that the outcome of stress may be negative for
an individual but positive for the population. For
example, mortality of individual fish due to exhaustion
from over crowding may actually enhance survival of
the population when space or food supplies are limiting.
According to Esch and Herzer (1998) stress, then
can better be defined as “the effect of any
environmental alterations or force that extends
homeostatic or stabilizing processes beyond their
normal limits, at any level of biological organization”.
While Barton (1997) defined stress as “the response of
the cell, or organism, to any demand placed on it such
that it causes an extension of a physiological state
beyond the normal resting state”. According to
Chrousos (1997), stress in fish can be considered as a
state of threatened homeostasis that is re-established by
a complex of adaptive responses. If the intensity of the
stressor is overly severe or long lasting, however,
physiological response mechanisms may be
compromised and it can become detrimental to the
fish’s health and well being, or maladaptive a state
associated with the term “distress” (Barton and Iwama
1991; Barton 2002).
Stress can be physical, psychological or
environmental. It can either be short and sudden or long
and chronic. While mild, short-term stress has few
serious health effects, compared to long-term stress, it
should be noted that short-term stress contribute to
many of the illnesses and deaths in aquarium fish
(Tullock, 2001). This description is based on the type of
stressors acting on the fish specifically over a period of
time.
Table 1. World fisheries and aquaculture production
Production (million tones) 2000 2001 2002 2003 2004 2005
Inland
Capture 8.8 8.9 8.8 9.0 9.2 9.6
Aquaculture 21.2 22.5 23.9 25.4 27.2 28.9
Total Inland 30.0 31.4 32.7 34.4 36.4 38.5
Marine
Capture 86.8 84.2 8.4.5 81.5 85.8 84.2
Aquaculture 14.3 15.4 16.5 17.3 18.3 18.9
Total Marine 101.1 99.6 101.0 98.8 104.1 103.1
Total Capture 95.6 93.1 93.3 90.5 95.0 93.8
Total Aquaculture 35.5 37.9 40.4 42.7 45.5 47.8
Total World Fisheries 131.1 131.0 133.7 133.2 140.5 141.6
3. Stressors common in fish cultivation
Stressors are real or perceived challenges to an
organism’s ability to meet its real or perceived needs
(Greenbery et al., 2002). Fishes are exposed to
stressors in nature as well as in artificial conditions
such as in aquaculture or in the laboratory (Iwama et al.,
2006). Stressors that challenge homeostasis, often
regarded as the most urgent of needs are the best
known (Table 2). When an organism’s capability to
maintain homeostasis within a specific range is
exceeded, responses are evoked that enabled the
organisms to cope by either removing the stressor or
facilitating co-existence with it (Antelman and
Caggiula, 1990).
Fish under intensive culture conditions are
exposed to a regime of acute and chronic stressors,
which have adverse effects on growth, reproduction
immunocompetence, and flesh quality (Barton et al.,
1987; Maule et al., 1989; Shreck et al., 2001). These
stressors, which are peculiar to fish in aquaculture
range from chemical, biological, physical and
procedural. The most prevalent which induce stress in
fish is the procedural stressors, from daily management
practices in fish farming (Table 2).
3. Indicators of stress in fish
There are various direct and indirect quantitative
parameters used as indicators of stress in fish (Barton
and Iwama, 1991). This ranges from physiological
status to physical observations on the fish (Table 3.).

Researcher, 2011;3(4) http://www.sciencepub.net/researcher
http://www.sciencepub.net/researcher researcher135@gmail.com
30
These include changes in the level of cortisol in the
plasma, alterations in immunoglobulin levels, and
changes in the haematological parameters. As in other
vertebrates, the blood concentration of costicosteroid
hormones is a major index of stress in fish and elevated
levels of these hormones arise from activation of the
hypothalamus-pituitary-internal (HPI) axis
(Wendelaar-Bonaga, 1997). Physical signs of stress
from observation differs with stressors and varies from
one species of fish to another.
4. Fish responses to stress in aquaculture
Fish responses to stressors in aquaculture vary
according to the source, effect, environment and
characteristics of stressor (Akinrotimi et al., 2009).
However, the features of stress reactions are generally
common to most forms of stressors. Stress response of
fish is an integrated reaction with behavioural, neural,
hormonal and physiological elements all combined
together to provide fish with the best possible chance
of survival (Pickering, 1993). Also, Akirontimi et al.
(2007c) observed that male and female fish differs in
the way they response to stress. Therefore sex is a
crucial factor in the way fish respond to stress.
Physiological responses of fish to environmental
stressors have been grouped broadly as primary,
secondary and tertiary (Barton, 2002).
4.1. Primary Response
Stress reaction arises from the activation of the
sympathetico-chromaffin system and the hypothalamic
pituitary-interrenal axis (Pickering, 1981). Changes
of parameters of these systems are named as primary
stress responses (Vosyliene and Kazlauskiene, 1999).
Primary response involves the initial neuroendocrine
responses, and include the release of catecholamines
from chromaffin tissues (Randall and Perry, 1992; Reid
et al., 1998) and the stimulation of the
hypothalamic-pituitary-interrenal (HPI) axis
culminating in the release of stress hormones,
cathecolamines and cortisol circulation (Wendelaar
Bonga, 1997; Mommsen et al., 1999). Cortisol is
released from the interrenal tissue located in the head
(anterior) kidney, in response to several pituitary
hormones, but most potently to adrenocorticotrophic
hormone, ACTH (Balm 1997). The approximate
resting and stressed levels in the plasma of salmonids
are between 20-70 nmoles/L for adrenaline, and
40-200ng/ml for cortisol (Iwama et al, 2004). These
values may serve as general basal data. Individual
conditions including species differences, general
characteristics, prior rearing history and local
environment will modify the plasma values for control
and stressed states (Barton et al., 2002).
4.2. Secondary Response
This response includes changes in plasma and
tissue ion and metabolic levels, haematological features,
and heat shock or stress proteins (HSPs) all of which
related. Plasma cortisol concentrations in selected
juvenile freshwater fishes before and one hr after being
subjected to an identical 30-sec aerial emersion,
handling stressor to physiological adjustments such as
in metabolism, respiration, acid-base status,
hydromineral balance, immune function and cellular
responses were also affected (Pickering, 1981; Iwama
et al., 1997; 1998; Mommsen et al., 1999; Barton, et al.
2002). In this type of response the stress hormones
activate a number of metabolic pathways (Table 4) that
result in alterations in blood chemistry and
haematology (Randall and Perry 1992; Vijayan et al.;
1994; Iwama et al., 2004).
Also, worthy of mention is the plasma glucose
concentration which often times has been used as an
indicator of stressed state in fish, and perhaps may be
the most commonly measured secondary response
parameters to stressors in fish (Barton et al., 2002).
According to Iwama et al., (2006) the plasma
glucose concentration in circulation is dependent upon
glucose production and its clearance from the
circulation. The glucose produced, when fish is under
stress supplies energy to tissues such as the brain, gills
and muscles in order to cope with the increased energy
demand. Liver is the main source of glucose production
and is achieved by glycogenolysis or
gluconeogenenesis. Adrenalin and cortisol have been
linked to increased glucose production in fish (Vijayan
et al., 1994).
4.3. Tertiary Response
Tertiary response refer to aspects of whole animal
and population level performance such as changes in
growth, condition, overall resistance to disease,
metabolic scope for activity, decreased reproductive
capacity and ultimately survival (Wedemeyer and
McLeay, 1981; Wedemeyer et al. 1990; Iwama et al.
2004). All these alterations according to Barton et al.
(2002) may be associated with stress. Mediated
energy-repartitioning that diverts energy subtrates from
vital life processes, such as reproduction and growth in
order to cope with the enhanced energy demand
associated with stress, have detrimental consequences
on cultured species.

Researcher, 2011;3(4) http://www.sciencepub.net/researcher
http://www.sciencepub.net/researcher researcher135@gmail.com
31
Table 2. Stressors common in intensive aquaculture
S/No. Stressor Occurrence (%)
A Chemical stressors
1. Poor water quality (Low DO., improper pH) 20
2. Pollution- intentional pollution: efficient, wastes, sewage;
-accidental pollution: spills: insecticide, pesticide 10
3. Diet composition imbalance diet 10
4. Nitrogenous and other metabolic wastes i.e accumulation of
ammonia or nitrite 35
B Biological stressors
1. Population density over crowding 5
2. Social dominance 1
3. Micro organisms–pathogenic and non pathogenic 2
4. Macro organisms-internal and external parasites 2
C Physical stressors
1. Temperature 1
2. Light 1
3. Sounds 0
4. Dissolved Gases 1
D Procedural stressors
1. Handling 3
2. Transportation 5
3. Sorting/Grading 3
4. Disease Treatments 1
Source: Field Survey (2007)
Table 3. Indicator of stress in some teleost fish
Species Stressor Indicator of Stress References
Sarotherodon
melanotheron Confinement Reduced Haemoglobin increased
differential count Gabriel et al. (2007b)
Gabriel et al (2007c)
C. gariepinus Acclimation Distortion in blood parameter Gabriel et al. (2004)
S. melanotheron Salinity changes Increased WBC
Reduced RBC Anyanwu et al. (2007)
S. melanotheron
Tilapia guirenesis Transportation
Transportation Distortion in blood parameters Akinrotimi et al. (2007c)
Akinrontimi et al. (2009)
Oreochromis niloticus Transportation Reduced PCV Orji (2005)
Sceianops ocellatus Transportation Hormonal dysfunction Robertson et al. (1987)
C. gariepinus
fingerlings Poor water quality Vertical swimming Field survey (2007)
C. gariepinus
/hybrid/ O. niloticus Fertilizer effluents Altered tail/opercular beat
frequencies/increased mucus
production
Bobmanuel et al. (2006)
C. gariepinus Chemical Distortion in tissue chemistry Onusiriuka and Ufodike
(2000)
C. gariepinus Chemical Reduced plasma enzyme activities Gabriel and George (2006)
Tilapia guineensis
Industrial effluents
Reduced leucocyte levels Davids et al. (2002)
C. gariepinus Chemotheurapetants
Changes in blood component Musa and Omoregie (1999)
O. niloticus Chemotherapeutants
Depression of haemopoesis Omoregie and Oyebanji
(2002)
Salvinus calpinous Chemotherapeutants
Spinal deformities Toften and Jobling (1996)
C. gariepinus Crude oil Distortion of haematocrit and
haemoglobin Gabriel et al. (2001)

Researcher, 2011;3(4) http://www.sciencepub.net/researcher
http://www.sciencepub.net/researcher researcher135@gmail.com
32
5. Efects of stress in cultured fish
The effects of stress in cultured fish ranges from
alteration of fish defence mechanisms decreased
protective barriers of fish, damaging of scales and skin,
inflammation and antibody production. Stress, induced
by handling or chemical (disease treatment) often
causes some changes in mucus which decreases its
effectiveness as a chemical barrier against invading
organisms. Stress upsets osmoregulation by disrupting
the normal electrolyte (sodium, potassium and chloride)
balance which results in excessive uptake of water by
fresh water fish and dehydration in salt water fish,
thereby disrupting energy balance (Maule, 1994; Norris,
2000). Scales and skin are the most commonly damaged
by handling stress. Any injury to the skin or removed
scale creates on opening for invasion by pathogenic
organisms.
Stress according to Akinrotimi et al. (2007c) often
in extreme cases lead to mortality, which is more
pronounced in the early stage of the fish life (Table 5)
because they are more fragile and vulnerable to external
stressors. But as they advance, the effect of stress
becomes reduced, but often manifests in retarded
growth, impaired reproductive ability in tilapias and
some other fish that breed in captivity.
6. Remedy for controlling stress
Considering the devastating effect stress can have
in cultured species, the challenge before the
aquaculturists is to develop strategies that will
maximally reduce stress in cultured species so as to
enhance sustainable aquaculture production. Although
in aquaculture practices, the strategies for handling
acute and chronic stress may differ, as their level of
intensity differ (Tullock, 2001). The cultured fish may
appear to be doing well, until one day gets sick and dies,
and then a few weeks later another one, and so on, until
the whole stock is affected (Stoskopf, 1993). If there is
any mortality in the fish stock, there is probably a
source of stress that needs to be identified and remedied.
This can be done in one or more of the following ways
or combination of the options:
Table 4. Responses of rainbow trout to different stimuli and their combined action
Parameters Stimuli
Chemical Starvation Confinement
Morphological:
Weight of fish * *
Weight of tissues * *
Condition factor * **
Tissue-somatic indices *
Cardio-respiratory **
Ventilation frequency * **
Heart rate * **
Meant RR interval duration * **
Rhythm stability index **
Ventilation waves
Haematological:
Erythrocytes * *
Leucocyte * * **
Haemoglobin * **
Haematocrit * **
Glucose * **
Neutrophyls * **
* Significant differences from the control (p < 0.05), ** Extremely significant differences from the control (p <
0.01)
Source: (Vosyliene and Kazlaoskiene, 1999, Gabriel et al 2007a).
6.1. Maintenance of good water quality in culture medium
Good water quality involves preventing accumulation of organic debris and nitrogenous wastes, preventing
ammonia build up, maintaining appropriate pH and temperature depending on the species that is being cultured
(Table 6). It also involves most importantly maintaining dissolved oxygen levels of at least 5mg/L.
6.2. Appropriate stocking density
To avoid unnecessary stress, fish should be stocked at appropriate stocking density (Table 7). The stocking rate
is the number of fish, which a pond can hold and maintain without exceeding its carrying capacity. The stocking

Researcher, 2011;3(4) http://www.sciencepub.net/researcher
http://www.sciencepub.net/researcher researcher135@gmail.com
33
density therefore depends on the species and the culture systems that are being utilized. Appropriate stocking density
prevents the fish from over crowding which often leads to struggling for food, oxygen and survival and ultimately
culminates in stress.
Table 5. Effects of stress on different life stages of fish.
Stages of fish Stress Effect
Fry Devastating, with high mortality
Fingerlings Very fatal, with high mortality
Juveniles Moderate mortality, reduced growth rate
Adult Less effect compared to juveniles reduced growth rate
Brood Fish Less gravid
Field survey, 2006
Table 6. Some favourable water quality ranges of commonly cultured species in aquaculture
Species pH DO (mg/l) Temperature (0C)
Salinity (0/00)
Clarias gariepinus 6.5-9.5 >0.67 15-35 0-0.5
T. guineensis 5.5-9.6 >0.41 14-33 0-35
Sarotherodon melanotheron 5.4-9.8 >0.41 15-34 0.1-35
Oreochromis niloticus 6.8-100 >0.42 10-35 0.1-1.0
Mugil cephalus 5.5-10.0 >0.46 14-33 5-35
Chrysichthys nigrodigitatus 5.6-9.0 >0.63 18-33 0-35
Ictalurus punctatus 6.5-10.0 >0.66 10-33 0-0.6
Cyprinus carpio 6.7-10.0 >0.65 10-33 0-0.6
Chanos chanos 6.8-10.2 >0.41 10-30 0-0.8
Megalops atlanticus 5.5-9.8 >0.40 10-35 0-36
Source: Boyd (1982)
6.3. Balanced diet
Fish should be fed with a high quality diet that meets their nutritional requirements depending on the
species, age, size and production function (Table 8).
Balanced and complete feed have been observed by Tacon (1994), as an appropriate way of eliminating
nutrititional induced stress in fish. The vitamin C included diet, has been observed by Ibiyo et al. (2006) to reduce
stress to the barest minimum in Heterobranchus longifilis.
6.4. Proper sanitation
This implies routine removal of debris from fish tanks, and regular disinfection of containers, nets and other
equipments between groups of fish, especially after harvesting and before new stock arrived (Table 9). The culture
medium should be washed, cleared and disinfected. It should be noted that organic debris which accumulate at the
bottom of tanks is an excellent medium for reproduction of fungal, bacteria, and protozoan agents. Prompt removal
of debris will help reduce the number of pathogens and hence pathogen-induced stress.
Table 7. Stocking density of some culturable fishes in earthen and tank culture system.
Species Earthen pond (103fish /ha) Concrete tank (No of fish/ m3)
C. gariepinus 26.6-10 30-40
T. guineensis 10-20 20-40
Heterotis niloticus 3.5-8 --
O. niloticus 10-20 20-40
Cyprinus carpio 3-6 20-30
Sarotherodon melanotheron 15-25 20-30
Source: Adesulu (2001).

Researcher, 2011;3(4) http://www.sciencepub.net/researcher
http://www.sciencepub.net/researcher researcher135@gmail.com
34
6.5. Usage of Anesthetics
Anesthetics can be used to minimize stress during transportation, breeding and other farm activities. It is
used to sedate bigger fish during breeding, so as to minimize stress. Also, during out break of any disease,
anesthetics could first of all be used to stabilize the fish before proper treatment is applied. Selected anesthetics and
estimates for optimum doses, as well as induction and recovery times for various fishes are shown in Table 10.
6.6. Proper Management of Fish during Transportation
To alleviate stress due to transportation, fish should be transports very early in the morning or late in the
evening. Of recent, air conditioned vehicles, are being used to transport fish over a long distance, to reduce mortality
as a result of stress (Table 11).
Table 8. Dietary protein and energy levels resulting in highest growth rates in various fish species (% of dry diet)
Fish species Crude dietary protein
(%) Gross dietary energy
(kj/g)
Chinook salmon (Oncorhynchus tshawytscha) 40-55 19.3-20.4
Rainbow trout (Oncorhynchus mykiss) 40-45 19.1-20.8
Estuary grouper (Epinephelus salmoides) 40-50 14.3-18.1
Gilthead bream (Pagrus auratus) 40-45 22.5-23.2
Red sea bream (Pagrus major) 55-40 21.1-22.2
Smallmouth bass (Micropterus dolomieui) 45-50 18.4
Striped bass (Morone saxatilis) 47-55 24.8
African catfish (Clarias gariepinus) 40-45 18.6
Asian catfish (Clarias batrachus) 30-35 17.2
Channel catfish (Ictalurus punctatus) 35-40 11.5-16.9
Common carp (Cyprinus carpio) 31-40.6 12.8-22.7
Indian major carp (Labeo rohita) 34-36 15.5
Tilapia (Oreochromis aureus) fingerling 34-36 13.4
Tilapia (Tilapia zilli) 30-35 21.8
Tilapia hybrid (O. niloticus x O. aureus) 30-35 17.3
Mullet (Mugil cephalus) 28-30 11.0
Milkfish (Chanos chanos) fry 40-45 15.3
Source: Data adapted from Tacon (1990), De Silva and Anderson (1995); Hassan et al. (1996)
CONCLUSION
With the recent upsurge in the world population, especially in the developing countries and the corresponding
increase in the need for cheap source of food to satisfy the protein need of the people, coupled with the declining
yield in capture fisheries, there has been a massive intensity on aquaculture, as a veritable option in realizing this
goal. This level of intensity which involves various ways of handling fish, translates to more stress for the fish. To
sustain and increase the yield from aquaculture practice there is the need to create the awareness and understanding
of what constitutes stress in fish, notably in the area of physiological mechanism and responses that lead to changes
in metabolism, growth, immune functions, reproductive capacity and normal behaviour.
Table 9: Cleaning routines in fish farming
S/no. Equipment/material Frequency/time of cleaning
1 Earthen Pond bottom Desilt pond bottom once a year after harvesting
2 Tank bottom Regular removal of debris depending on the age of the fish
3 Nets Regular washing and drying of nets
4 Farm tools Regular washing and cleaning of tools used in the farm
5 Tanks Tanks should be washed at least once in every three months
6 Farm surrounding Farm environment should be cleared and cleaned regularly.
Source: Field survey (2007)
The indices of fish responses to stimuli varied in their responsiveness to various types of stressors in
aquaculture. This is because the effect of different stimuli can occur in an organism through different physiological
systems. Different stressor when affecting fish separately cause responses, which can be reversible when appropriate

Researcher, 2011;3(4) http://www.sciencepub.net/researcher
http://www.sciencepub.net/researcher researcher135@gmail.com
35
steps are taken to ameliorate the trend. However, it must be well understood that the response of fish to a stressor is
a dynamic process that need to be seriously looked into by fish biologists and aquaculturist. If this is done properly,
it will undoubtedly increased production and leads to sustainability of aquaculture industries in the world.
Table 10. Selected anesthetics and estimates for optimum doses, as well as induction and recovery times for various fishes.
Anaesthetic Dose Induction
time Recovery time Test fish References
25-100 <3 min <10 min Salmonids, Carp,
Minnows (Yesaki, 1988)
250-480 mg/l <5min <10min Atlantic salmon (Malmstroem et al.
1993)
75 mg/l Rapid 3.7-7.1 min Cod (Mattson and Ripple,
1989)
MS 222
80-100 mg/l 2.6-6.8 min 2.5-1.2min Tilapia (Ferriera et al. 1979;
Ross and Ross, 1984)
40mg/l Cod (Ross and Ross, 1984)
25-50 mg/l 3min 4.3-6.32 min Salmonids (Yesaki, 1988)
55-85 mg/l 3 min <10 min Bass
Benzocaine hydrochloride
50-100 mg/l 1.2-3.9
1.6-6.5 min 3.1-2.2
2.9-2.2 min Carp
Tilapia (Ferriera et al. 1979)
Lidocaine plus 350 mg/l 53 see 13min Carp (Carrasco et al. 1984)
Sodium bicarbonate pH 6.5 + 642mg/l
NaHCo3 5min 10min Carp (Booke, 1978)
900 mg/l 5min 12.1min Adult salmon (Gilderhus and
Marking, 1987)
Metomidate 5-20mg/l <3min Rapid Cod
Propoxate 1-4mg/l <10min (Ross and Ross, 1984)
Quinaldine sulfate 15-40 mg/l 2-4min 1-20min Salmonids Gilderhus and
Marking, 1987.
Propanidid 1.5-3mg/l 1-4min 4-10min Salmonids (Siwicki, 1984)
Clove oil and AQUI-S 40mg/l 2.5-4min 3min Rainbow trout
(FW, 110C) (Anderson et al.,
1997)
40-60mg/l 3-4min 12-14min Raibow trout (FW,
90C) (Keene et al., 1998)
Correspondence to:
Ojo Andrew Akinrotimi,
African Regional Aquaculture Centre/Nigerian
Institute for Oceanography and Marine Research,
P.M.B. 5122,. Port Harcourt, Nigeria.
Cellular phone: +234-806-577-0699
Emails: ojoakinrotimi@yahoo.com
References
[1] Akinrotimi, OA; Gabriel UU, Owhonda NK,
Onunkwo DN; Opara, JY Anyanwu P, Cliffe PT.
Formulating an environmentally friendly fish feed for
sustainable aquaculture development in Nigeria. Agric.
J. 2007; 2(5) 606-612.
[2] FAO. State of world aquaculture 2006 FAO
Fisheries Technical Paper, No. 500, Rome, 2006;
134pp.
[3] FAO. State of world Fisheries are Aquaculture
(SOFIA), FAO, Rome Italy. 2005; 120pp.
[4] FAO. Database on Introduced Aquatic Species
FAO Database on Introduced Aquatic Species,
FAO, Rome. 2002 (variable pp.)
[5] NACA/FAO. Aquaculture development beyond:
The Bangkok declaration and strategy, conference
on aquaculture in third millennium, 20-25
February 2000. Bangkok, Thailand. NACA,
Bangkok and FAO Rome. 2000
[6] Boyd C, Massaut EL, Wedding LJ. Towards
reducing environmental impacts of ponds
aquaculture. INFOFISH International 98; 2:
27-23.
[7] Savas, I. 1998. Current status and outlook of the
aquaculture industry. Pp. 288-308. In: Saves L. (ed)
Improving management of Aquaculture in Asia.
Report of an APO Seminar. 8-16 May 1996:
Taipei, Republic of China.
[8] Jamu, DM; Ayinla OA. Potential for development
of aquaculture in Africa. NAGA World Fish
Center Quarterly 2003; 26(3): 9-13.
[9] Angelids P, Baudin-Laurecin T, Youinou S. Stress
in rainbow trout Salmo gairdineri, effects upon
phagocytes and susceptibility to Aeromonas.
salmonicida J. Fish. Biol. 1987; 31: 113-122.
[10] Gabriel U. U.; P. E. Anyanwu and O. A.
Akinrotimi. Blood characteristics associated with

Researcher, 2011;3(4) http://www.sciencepub.net/researcher
http://www.sciencepub.net/researcher researcher135@gmail.com
36
confinement stress in black chin tilapia
Sarotherodon, melanotheron. J. Fish. Int. 2007a ;
2:186-189.
[11] Pickering AD, 1981. Stress and fish Pp. 11-124,
Academic Press New York, 367pp.
[12] Maule AG, Shreck CB. Changes in number of
leucocytes in immune organs of juvenile coho
salmon after acute stress of contisol treatment. J.
Aquacult. Anim. Health 1990;2: 298-304.
[13] Ellsaesser, C. F. and L. W. Clem. 1986.
Haematological and Immunological changes in
catfish stressed by handling and transport. J. Fish
Biol.. 28:511-521.
[14] Ainsworth AJ; Dexlang C, Waterstrat PR..
Changes in peripheral blood leukocyte
percentages and function of new cells in stressed
Channel catfish. J. Aquacult. Anim. Health.
1991; 3:41-47.
[15] Pickering, A. D. and T. C. Pottinger. Poor water
quality suppresses the cortisol response of
salmonid fish to handling and confinements. J.
Fish Biol. 1985; 30: 363-374.
[16] Maule, AG.; Tripp RA; Kaatarist,AY; Shreck
CB 1989. Stress alters immune functions and
disease resistance in Chinook Salma
(Oncorhynchus tshawytscha) J. Endocrinol 120:
135-142.
17] Foster F, Smith S. Stress and fish health
http:www.liveaquaria.com Assessed 16th Sept.
2007.
[18] Stoskopf, MK. 1993. Fish Medicine, W. B.
Saunders Co. Philadelphia. 366pp.
[19] Seyle, H. C. 1950. Stress and the general
adaptation syndrome. Brit Med. J., 1:13-18.
[20] Wedemeyer, G.A.; Barton BA, Mcleay DJ. Stress
and acclimation. In: Shreck CB, Moyle PB
(eds.). Pp. 451-489. Methods for fish biology.
Am. Fish Soc.. 1990
[21] Esch, GW, Hazen TC. Thermal ecology and
stress: a case history for red-sore disease in large
mouth bass. Pp. 331-363. In: energy and
environmental stress in aquatic ecosystems.
Thorp JH, Gibsons JW (eds). Technical
Information Centre, U.S. Department of Energy.
Conf. 77114. 1978;
[22] Barton, BA. Stress in finfish: Past present and
future- a historical perspective: Pp. 1-33. In:
Iwama GK, Pickering, AD Sumpter JP, Shreck
CB (eds), Fish stress and health in aquaculture,.
Cambridge University Press. Cambridge. 1997.
[23] Chrousos, G.P. 1997. The neuroendocrinology of
stress: Its relation to the hormonal milieu, growth
and development. Growth Genet. Horm. 13:1-8.
[24] Barton, BA, Iwama GK. Physiological changes in
fish from stress in aquaculture with emphasizes
on the response and effects corticosteroids.
Ann. Rev. Fish Dis. 1991; 1:3-26.
[25] Barton, BA.. Stress in Fishes: A diversity of
response with particular reference to changes in
circulating corticosteroids. Integ, Comp. Biol.
2002; 42:517-525.
[26] Tullock, JH 2001. Natural Reef Aquaring. TFH
Publications, Neptune City, NJ.;
[27] Greenberg, N.; J.A. Carr and C. H. Summers.
Causes and consequences of stress Integ. Comp.
Biol. 2002; 42: 508-516.
[28] Iwama, G.K;., Afonso LOB, Vijayan MM. Stress
in fishes pp 319 In: Evans DH, Claiborne JB (eds)
The physiology of fishes. CRC Press Taylor and
Francis, Boca Raton. Florida. 2006; 601pp.
[29] Antelman, SM, Caggiula AR. Stress Induced
behaviour: Chemotherapy without drugs Pp.
65-104. In: Davidson JM, Davidson RJ (eds.).
The Psychobiology of Consciousness. Plenum
Press, New York. 1990.
[30] Barton BA, Shreck CB, Barton LD. Effects of
chronic cortisol administration and daily acute
stress on growth, physiological conditions and
stress responses in Juvenile rainbow trout. Dis
Aquat Org. 1987; 2:173-185.
[31] Shreck CB; Wilfreds C, Fitzpatrick MS. Effect of
stress on fish reproduction, gamete quality and
progeny. Aquaculture 2001; 197:3-24.
[32] Gabriel UU, Anyanwu PE, Akinrotimi OA..
Effect of Freshwater challenge on the Blood
characteristics of Sarotherodon melanotheron
Agric J. 2007b; 2(3): 388-391.
[33] Gabriel UU, Anyanwu PE, Akinrotimi AO.
Comparative effects of different acclimation
media on haematological characteristics of
brackish water Tilapia Sarotherodon
melanotheron (Rupell, 1852) J. Fish. Intl. 2007c ;
2(3): 195-199.
[34] Gabriel UU Ezeri GNO, Opabunmi OO..
Influence of sex, source health status and
acclimation on the haematology of Clarias
gariepinus. Afri. J. Biotech. 2004; 3: 463-467.
[35] Anyanwu PE, Gabriel UU, Anyanwu AO,
Akinrotimi AO. Effect of salinity changes on
hematological parameters of Sarotherodon
melanotheron from Buguma creek, Niger Delta. J.
Anim. Vet. Adv. 2007; 6(5): 658-662.
[36] Akinrotimi OA; Gabriel UU, Anyanwu PE,
Anyanwu AO. Influence of sex, acclimation
methods and period on haematology of
Sarotherodon melanatheron. Res. J. Biol. Sci
2007c; 2(3):348- 352
[37] Akinrotimi, OA; Abu OMG, Ansa EJ, Edu OM,
George OS. Haematological response of Tilapia
guineensis to acute stress. Int. J. Natural and
Appl. Sci. 2009; 5(4): 338-343.
[38] Orji RCA. The effect of transportation stress on

Researcher, 2011;3(4) http://www.sciencepub.net/researcher
http://www.sciencepub.net/researcher researcher135@gmail.com
37
haematocrit level of Oreochromis niloticus. A
min. Res. Int. 2005; 2: 224-226.
[39] Robertson L, Thomas CR, Arnold,TY and Trant
JM Plasma cortisol and secondary stress
responses of red drum to handling transport
rearing density and disease out break. Prog. Fish
Cult. 1987; 49: 1-12.
[40] Bobmanuel NOK; Gabriel UU and Ekweozor
IKE. Direct toxic assessment of treated fertilizer
effluents to Oreochromis niloticus and Clarias
gariepinus and catfish hybrid (Heterobronchus
bidorsalis and Clarias gariepinus). Afri. J.
Biotech. 2006; 5(8): 635-642.
[41] Onusiriuka BC, Ufodike EBC. Effects of
sublethal concentrations of Akee apple Bilghia
sapida and Sausage plant, Kigelia africana on
tissue chemistry of African catfish, Clarias
gariepinus. J. Aquat Sci 2000; 15:47-49.
[42] Gabriel UU, Anyanwu PE, Akinrotimi OA.
Effect of Freshwater challenge on the Blood
characteristics of Sarotherodon melanotheron.
Agric J. 2007b 2(3): 388-391.
[43] Davids CBB, Ekweozor IKE, Daka ER; Dambo
WB, Bartimaeus EAS. Effects of industrial
effluents on some haematological parameters of
Sarotherodon melanotheron and Tilapia
guineensis. Global J. Pure Applied Sci. 2002;
8(3) 305-310.
[44] Musa SO, Omoregie E, Haematological changes
in the mudfish Clarias gariepinus exposed to
malachite green. J. Aquatic sciences. 1999; 14:
378-40.
[45] Omoregie E, Oyebanji, SM.
Oxytetracycline-induces blood disorder in
Juveniles of Nile Tilapia Oreochromis niloticus.
World Aquaculture. Soc. 2002; 33:377-382.
[46] Toften L. and Jobling, M. 1996. Development of
spinal deformities in Atlantic salmon and Artic
Char, feed diet with oxytetracycline J. Fish Biol.
49: 668-677.
[47] Gabriel UU, Anyanwu PE,. Akinrotimi AO.
Comparative effects of different acclimation
media on haematological characteristics of
brackish water Tilapia Sarotherodon
melanotheron (Rupell, 1852) J. Fish. Intl. 2007c;
2(3): 195-199.
[48] Pickering, A. D.. Growth and stress in fish
production. Aquaculture 1993; 111: 51-63.
[49] Vosyliene M.Z, Kazlauskiene N. Alterations in
fish health state parameters after exposure to
different stressors. Acta Zool. Lituanica
Hydrobiologia 1999; 9(2): 83-94.
[50 Randall, D. J. and S. F. Perry. Catecholamine in
fish physiology, Vol. XII B. Hoar WS, Randall
DJ, Farrell TP (eds.), Academic press New York.
1992; 255pp.
[51] Reid, SG, Bernier NJ, Perry SF. The adrenergic
stress response in fish: control of catecholamine
storage and release. Comp. Biochem. Physiol.
1998; 120C: 1-27.
[52] Wenderlaar-Bonga SE. The Stress response in
fish. Physiol Rev.; 77:591-625.
[53] Mommsern TP, Vijayan MM, Moon TW..
Cortisol in teleosst: dynamics, mechanisms of
action and metabolic regulation. Rev. Fish Biol.
1999; 9:211-268.
[54] Balm PHM. Adrenocorticotropic hormone in
relation to interrenal function during stress in
tilapia (Oreochromis mossambicus). Gen. Comp.
endocrinol. 1997; 96:110-116
[55] Iwama, GK, Afonso LOB, Vijayan, MM. Stress
in fish (Aqua Net) Workshop on fish Welfare
September 27. 2004; 9pp.
[56] Barton BA; Morgan JD, Vijayan MM, 2002.
Physiological and condition-related indicators of
environmental stress in fish. Pp.111-116. In:
Adam SM (ed) Biological indicators of aquatic
ecosystems stress. Amer. Fish. Soc. Bethesda.
[57] Iwama GK, Pickering AD, Sumpter JP, Schreck
CB.. Fish stress and Health in Aquaculture. Soc.
Exp. Biol. Sem. Ser. 62. Cambridge Univ. Press,
Cambridge U.K. 1997; 306pp.
[58] Vijayan, MM; Moo TW, Mommsen, YY. The
effect of contisol on hepatocyte metabolism in
rainbow trout: a study using the steroid analique.
Gen. Comp. Endocrinol. 1994; 96(75):
1112-1132.
[59] Wedemeyer GA, McLeay DJ. Methods for
determining the tolerance of fishes to
environmental stressors, Pp. 247-268. In: A.D
Pickering (ed). Stress and fish. Academic Press.
London. 1981; 367pp.
[60] Norris, DO. Endocrine disruptors of the stress
axis in national populations: how can we tell?
Amer. Zool. 2000; 40:393-401.
[61] Adesulu, EA. Pisciculture in Nigerian: essential
production information. Eternal communications
limited. Lagos. 2001; 118pp.
[62] Tacon, AGJ. Feed ingredient for crustaceans
natural foods and processed feed stuffs. FAO
Fisheries Circular 1994; 866:1-67.
[63] Ibiyo, L. M. O.; Madu C. T. and Eze S. S.
Growth response of Heterobranchus longifilis
fingerlings fed vitamin C-supplemented and
unsupplemented diets. Pp. 174-179. In: Ansa E.
J.; P. E. Anyanwu B. W. Ayonadu; E. S. Erondu
and S. N. Deekae (eds). Proceedings of the 20th
Annual Conference of the fisheries society of
Nigeria (FISON), Port Harcourt, 14th-18th
November, 2005. 2006.
[64] Tacon. A. G. J. 1990. Standard method for the
nutrition and feeding of farmed fish and shrimp,

Researcher, 2011;3(4) http://www.sciencepub.net/researcher
http://www.sciencepub.net/researcher researcher135@gmail.com
38
Washington Dc, Argent laboratory press, 454pp.
[65] Desilva SS, Anderson TA. Fish Nutrition in
aquaculture. Chapman and Hall, London. 1995.
[66] Yesaki T. A detailed description of the efficacy of
five anesthetics on juvenile Chinook salmon
(Oncorhynchus tshawytscha). 54pp. University
of British Columbia, Vancouver: Department of
Animal Science Report. 1988
[67] Hassan, MR; Ali MA; Akand AM, Ali, MM..
Nutritional requirements of Indian major carp
labeo rohita. Banglidog J. Aquacult 1996; 18:
24-31.
[68] Malmstroem T, Salte R, Gjoeen HM, Linseth A.
A practical evaluation of metomidate and
MS-222 as anaesthetics for Atlantic halibut
(Hippoglossus hippoglossus L.) Aquaculture
1993; 113 (4): 331-338.
[69] Lemm CA.. Evaluation of five anesthetics on
striped bass. National Fisheries Research Centre
Technical Report 196, 1993; 17pp. Kearneysville,
WV: National Fisheries Research Center
Freetown.
[70] Mattson NS, Ripple TH. Metomidate, a better
anesthetic for cod (Gadus morhua) in
comparison with benzocaine, MS-222,
chlorobutanol, and phenoxyethanol. Aquaculture
1989; 83 (1-2): 89-94.
[71] Ferriera J. T., Smit G. L., Schoonbee H. J. and
Holzapfel C. W. 1979. Comparison of anesthetic
potency of Benzocaine hydrochloride and
MS-222 in two freshwater species. Progressive
fish-Culturist 41 (3): 161-163.
[72] Booke HE. Sodium bicarbonate, an inexpensive
fish anesthetic for field use, Progressive
fish-Culturist 1978; 40 (1): 11-13.
[73] Gilderhus PA, Marking LL. Comparative
efficacy of 16 anesthetic chemicals in rainbow
trout. North American Journal of fisheries
Management 1987; 7:288-292.
[74] Siwicki A. New anesthetic for fish. Aquaculture
1984; 38 (2): 171-176.
[75] Anderson WG, Mckinley RS, Colavecchia M..
The use of clove oil as an anesthetic for rainbow
trout and its effects on swimming performance.
North American Journal of Fisheries
Management 1997; 17 (2):301-307.
[76] Keene JL, Noakes DLG, Moccia RD, Soto CG.
The efficacy of clove oil as an anaesthetic for
rainbow trout, Oncorhynchus mykiss (Walbaum).
Aquaculture Research 1998; 29 (2): 89-101.
2/18/2011