Insects in fish diets

Abstract

Implications
• Since the 1990s, the rising demand for fish products has been met by aquaculture rather than by capture fishery.
• Fish meal is the main component of many fish diets due to its outstanding nutritional value. As this reliance on fish meal is under question for environmental, societal, and economic reasons, alternative feed sources are required.
• Insects are rich in protein, energy, and lipids, and, unlike plant ingredients, are poor in fiber and anti-nutritional factors. Black soldier fly larvae, maggot meal, mealworm larvae, adult Orthoptera
(locusts, grasshoppers, and crickets), and silkworm pupae have been investigated for their nutritional attributes, ease of rearing, and biomass production. While not as ideal as fish meal, they
may be used to replace part of it in fish diets, usually less than 25 to 30% though greater rates are possible. Addition of synthetic amino acids could further enhance protein quality of insects.
• Further research on the nutritional value of insects for fish is needed. Industrial-scale processes for the production of insectbased fish diets have to be developed, taking into account their impact on the environment, food safety, and society.

Full text

Key words: alternative feeds, aquaculture, sh, sh feeds, insects
Introduction
There has been a major shift to diets with increased consumption of ani-
mal products, including sh. Indeed, people have never consumed so much
sh or depended so greatly on the sector for their well-being as today: in 2012,
sh provided 17% of the world population’s intake of animal protein. As cap-
ture shery production has been relatively stable at about 90 million tonnes
since the 1990s, the rising demand for shery products has been met by a fast-
growing aquaculture industry, which set an all-time high record at 67 million
tonnes in 2012, providing 50% of the sh used for human consumption (FAO,
2014). Fish feeds, notably those of salmonids and marine sh, are usually
based on sh meal and sh oil obtained from pelagic species captured for this
purpose (Médale et al., 2013). Fish meal is a highly regarded source of protein
with an excellent composition of essential amino acids, while sh oil provides
long-chain omega-3 fatty acids favored for their health benets (Olsen and
Hasan, 2012). However, this reliance on wild sh capture for sh farming is
under question. Not only sh meal and sh oil may contain contaminants such
as polychlorinated biphenyls and dioxins, but consumers are now interested
in sustainability metrics such as the ratio of wild shery inputs to farmed sh
outputs (Naylor et al., 2009). Also, the volatility and rise of sh meal prices
is a matter of concern for sh farmers (Olsen and Hasan, 2012). Furthermore,
while aquaculture’s share of sh meal and sh oil consumption has been in-
creasing, reaching 88% by 2007 (Tacon and Metian, 2008), the production of
sh meal decreased between 1994 and 2012 and is now about 5 to 6 million
tonnes (Médale et al., 2013; FAO, 2014). As a consequence, there has been
an ongoing search for alternative sources of protein that would allow aquacul-
ture to remain economically and environmentally sustainable (Barroso et al.,
2014). Non-animal proteins derived from legume and/or oil seeds or cereal
gluten are now introduced in sh diets (Médale et al., 2013), but plant sources
have limitations, such as palatability issues, presence of anti-nutritional sub-
stances, low concentrations of sulfur amino acids, and high proportions of
ber and non-starch polysaccharides (Sanchez-Muros et al., 2014).
In the recent years, insects have received wide attention as a potential
source of protein both for humans and livestock. Insects grow and repro-
duce easily, have high feed conversion efciency, and can be reared on bio-
wastes (van Huis et al., 2013; Makkar et al., 2014). One kilogram of insect
biomass can be produced from on average 2 kg of feed biomass (Collavo et
al., 2005). This article presents the current status on the insects that are the
best candidates as sh feed ingredients in partial or complete substitution
for sh meal, with regard to their nutritional attributes, ease of rearing, and
biomass production: larvae or pupae of Diptera black soldier y (Hermetia
illucens) and house y (Musca domestica); larvae of mealworm [Tenebrio
molitor (Coleoptera)]; adult Orthoptera from the Acrididae (locusts and
grasshoppers), Gryllidae (crickets), and Tettigoniidae (katydids) families;
and pupae of silkworm [Bombyx mori (Lepidoptera)]. Many sh species
consume insects in the wild: omnivorous species prey on insects found on
the bottom of water bodies whereas juvenile stages of carnivorous species
eat insects before switching to sh-based diets (Riddick et al., 2013).
Insect Composition
Protein and lipids
The main chemical constituents of insects are presented in Table 1.
The crude protein (CP) content of insects is high and varies from 42 to
63%, a range comparable to that of soybean meal but slightly less than
that of sh meal. Diptera larvae (black soldier y and housey) and meal-
worm larvae contain less protein than adult Orthoptera (locusts and crick-
ets) and silkworm pupae.
Insects often accumulate fat, especially during their immature stages
(Manzano-Agugliaro et al., 2012). The lipid content of non-defatted insects
is highly variable and varies from 8.5 (adult locust) to 36% (mealworm
larvae). However, variability in lipid concentration is high even within the
same species; for instance, oil values as high as 30% have been reported for
locusts because it is inuenced by the stage of development and by the diet
Insects in fish diets
G. Tran,† V. Heuzé,† and H.P.S. Makkar*
† Association Française de Zootechnie, Paris, France
*Food and Agriculture Organization of the United Nations, Animal Production and Health Division, Rome, Italy
© Tran, Heuzé, and Makkar
doi:10.2527/af.2015-0018
Implications
• Since the 1990s, the rising demand for sh products has been met
by aquaculture rather than by capture shery.
• Fish meal is the main component of many sh diets due to its
outstanding nutritional value. As this reliance on sh meal is
under question for environmental, societal, and economic rea-
sons, alternative feed sources are required.
• Insects are rich in protein, energy, and lipids, and, unlike plant in-
gredients, are poor in ber and anti-nutritional factors. Black sol-
dier y larvae, maggot meal, mealworm larvae, adult Orthoptera
(locusts, grasshoppers, and crickets), and silkworm pupae have
been investigated for their nutritional attributes, ease of rearing,
and biomass production. While not as ideal as sh meal, they
may be used to replace part of it in sh diets, usually less than 25
to 30% though greater rates are possible. Addition of synthetic
amino acids could further enhance protein quality of insects.
• Further research on the nutritional value of insects for sh is
needed. Industrial-scale processes for the production of insect-
based sh diets have to be developed, taking into account their
impact on the environment, food safety, and society.
Apr. 2015, Vol. 5, No. 2 37
Published March 30, 2015

(Barroso et al., 2014). The defatted meal, being richer in CP than soybean
meal and sh meal, could nd a place as a protein-rich resource in sh diets.
Carbohydrates
Insects contain relatively low levels of carbohydrates compared with
plants, typically less than 20% (Barroso et al., 2014). The carbohydrate most
commonly encountered by sh in the wild is probably chitin, a polymer of
glucosamine found in the exoskeleton of arthropods (Lindsay et al., 1984).
However, the amount of chitin in insects is variable because it depends on the
species and development stage and also on the method of analysis. Very high
[>10% of the dry matter (DM)] as well as very low values (<100 mg/kg DM)
have been reported (Finke, 2007). The ability of sh to digest chitin is also a
matter of debate. Chitinase activity has been observed in several sh species,
and benets of incorporating chitin into marine sh diets have been reported,
but it is generally agreed that chitin is one of the factors limiting the use of
insects in sh feeds (Ng et al., 2001; Sanchez-Muros et al., 2014).
Amino acids
The amino acid proles of various insects are given in Table 2. Com-
pared with sh meal, the CP of Orthoptera and mealworms tend to con-
tain less lysine while Diptera and silkworms are relatively rich in lysine.
Sulfur amino acids (in percent CP) tend to be less in insects than in sh
meal, except for silkworms. Threonine levels are roughly comparable but
are greater for silkworms. Tryptophan levels are generally less, except for
silkworms and housey maggot meal. For optimum growth, and depend-
ing on the specic requirement of the sh species, supplementation with
synthetic amino acids could therefore be recommended. Compared with
soybean meal, silkworms and Diptera have a globally better amino acid
prole and could be better substitutes of sh meal than soybean meal.
Minerals
Ash contents of insects are generally low, except for black soldier y lar-
vae, for which values greater than 15% have been reported. Black soldier y
larvae are rich in calcium (7.6% DM), but other insects have very low calcium
levels, and calcium supplementation would be required. Calcium fortica-
tion of the rearing substrate can increase the calcium level in larvae meals
(Table 1). Calcium:phosphorus ratios in insects vary from 0.2 to 1.2 (except
for black soldier y larvae, which have a ratio of 8.4) and are thus less than the
optimal values recommended for sh (1.1–1.4) (Chavez-Sanchez et al., 2000;
Kumar et al., 2012). In some insects (e.g., housey maggot meal and Mormon
cricket), phosphorus levels are particularly high (1.0 to 1.6%).
Fatty acid composition
The fatty acid proles of various insects are given in Table 3. Concen-
trations of unsaturated fatty acids are high in mealworm, house cricket, and
housey maggot meals (60–70%), and lowest in black soldier y larvae
(19–37%) due to high levels of saturated fatty acids. Linoleic acid (18:2n-6)
concentration is much greater than that of a-linolenic acid (APA , 18:3n-3), as
in many plant oils (including soybean and sunower). Compared with sh oil,
terrestrial insects contain greater quantities of n-6 polyunsaturated fatty acids
and negligible amounts of eicosapentaenoic acid (EPA, 20:5n-3) and docosa-
hexaenoic acid (DHA, 22:6n-3). This lack of EPA and DHA is a limiting factor
to the use of terrestrial insects in marine sh, which require these fatty acids but
have limited abilities to synthetize them. Salmonids can synthetize EPA and
DHA from APA, but dietary supply is more efcient (Médale et al., 2013; San-
chez-Muros et al., 2014). Aquatic insects, on the other hand, contain signicant
amounts of EPA and have been proposed as source of feed for freshwater sh
(Sanchez-Muros et al., 2014). For instance, the lipids of freshwater insects that
are part of the natural diet of the Atlantic salmon (Salmo salar) contain more
than 15% EPA (Bell et al., 1994). It has been shown that the lipid concentration
Table 1. Main chemical constituents in insect meals vis-à-vis fishmeal and soymeal (adapted from Makkar et al., 2014).
Constituents
Black soldier
y larvae
Housey
maggot meal
Mealworm
Locust
meal
House
cricket
Mormon
cricket
Silkworm
pupae meal
Silkworm pupae
meal (defatted)
Fishmeal
Soymeal
DM, %
Crude protein 42.1 (56.9)* 50.4 (62.1) 52.8 (82.6) 57.3 (62.6) 63.3 (76.5) 59.8 (69.0) 60.7 (81.7) 75.6 70.6 51.8
Lipids 26.0 18.9 36.1 8.5 17.3 13.3 25.7 4.7 9.9 2.0
Calcium 7.56 0.47 0.27 0.13 1.01 0.20 0.38 0.40 4.34 0.39
Phosphorus 0.90 1.60 0.78 0.11 0.79 1.04 0.60 0.87 2.79 0.69
Ca:P ratio 8.4 0.29 0.35 1.18 1.28 0.19 0.63 0.46 1.56 0.57
*Values in parentheses are calculated values of the defatted meals.
Black soldier y.
Lenny Worthington
38 Animal Frontiers

and the lipid prole of insects are highly dependent on the diet and that they
can be modied by changing the composition of the substrate (Sanchez-Muros
et al., 2014). For instance, changing the substrate from cow manure to a 50:50
mix of cow manure and sh offal increased the level of omega-3 fatty acids in
the black soldier y larvae from 0.2% to 2% (total fatty acids basis) and total
lipid concentration from 20 to 31% (DM basis) (St-Hilaire et al., 2007b).
Utilization of Insects in Fish Feeding
Black soldier fly larvae (Hermetia illucens)
Several experiments have shown that black soldier y larvae could
partially or fully substitute for sh meal in sh diets. However, additional
trials as well as economic analysis are necessary because reduced perfor-
mance has been observed in some cases and the type of rearing substrate
and the processing method affect their utilization by sh.
Channel catsh (Ictalurus punctatus). Chopped soldier y larvae
grown on hen manure fed to channel catsh alone or in combination with
commercial diets resulted in similar performance (body weight and total
length) as with the control diets. The sh aroma and texture were acceptable
to the consumer. Young catsh refused whole larvae but consumed chopped
ones (Bondari and Sheppard, 1981). Replacement of 10% sh meal with
10% dried soldier y larvae resulted in slower growth over a 15-wk period
for subadult channel catsh grown in cages but not in sh grown in tanks. In
tank-grown sh, feeding 100% larvae did not provide sufcient DM or CP
intake for good growth. Chopping of the larvae was not recommended, as
Table 2. Amino acid composition (g/16 g nitrogen) of insect meals versus FAO reference dietary protein requirement
values, soybean meal and fish meal (adapted from Makkar et al., 2014).
Amino acids
Black soldier
y larvae
Housey
maggot meal
Mealworm
Locust
meal
House
cricket
Mormon
cricket
Silkworm
pupae meal
Silkworm pupae
meal (defatted)
Fishmeal
Soymeal
FAO Reference
protein1
Essential
Methionine 2.1 2.2 1.5 2.3 1.4 1.4 3.5 3.0 2.7 1.32 2.502
Cystine 0.1 0.7 0.8 1.1 0.8 0.1 1.0 0.8 0.8 1.38
Valine 8.2 4.0 6.0 4.0 5.1 6.0 5.5 4.9 4.9 4.50 3.50
Isoleucine 5.1 3.2 4.6 4.0 4.4 4.8 5.1 3.9 4.2 4.16 2.80
Leucine 7.9 5.4 8.6 5.8 9.8 8.0 7.5 5.8 7.2 7.58 6.60
Phenylalanine 5.2 4.6 4.0 3.4 3.0 2.5 5.2 4.4 3.9 5.16 6.303
Tyrosine 6.9 4.7 7.4 3.3 5.2 5.2 5.9 5.5 3.1 3.35
Histidine 3.0 2.4 3.4 3.0 2.3 3.0 2.6 2.6 2.4 3.06 1.90
Lysine 6.6 6.1 5.4 4.7 5.4 5.9 7.0 6.1 7.5 6.18 5.80
Threonine 3.7 3.5 4.0 3.5 3.6 4.2 5.1 4.8 4.1 3.78 3.40
Tryptophan 0.5 1.5 0.6 0.8 0.6 0.6 0.9 1.4 1.0 1.36 1.10
Non-essential
Serine 3.1 3.6 7.0 5.0 4.6 4.9 5.0 4.5 3.9 5.18 -
Arginine 5.6 4.6 4.8 5.6 6.1 5.3 5.6 5.1 6.2 7.64 -
Glutamic acid 10.9 11.7 11.3 15.4 10.4 11.7 13.9 8.3 12.6 19.92 -
Aspartic acid 11.0 7.5 7.5 9.4 7.7 8.8 10.4 7.8 9.1 14.14 -
Proline 6.6 3.3 6.8 2.9 5.6 6.2 5.2 -4.2 5.99 -
Glycine 5.7 4.2 4.9 4.8 5.2 5.9 4.8 3.7 6.4 4.52 -
Alanine 7.7 5.8 7.3 4.6 8.8 9.5 5.8 4.4 6.3 4.54 -
1Reference for the 2-5 year old child.
2Methionine plus cystine.
3Phenylalanine plus tyrosine.
Blue tilapia feeding.
Brian Smith
Apr. 2015, Vol. 5, No. 2 39

it improved weight gain and increased feed consumption but resulted in re-
duced feed efciency and greater feed waste (Bondari and Sheppard, 1987).
A comparison between menhaden sh meal and black soldier y prepupae
meal showed that the latter could be advantageous up to an inclusion rate of
7.5% as a replacement for sh meal provided it was also supplemented with
soybean meal to obtain isoproteic diets (Newton et al., 2005).
Yellow catsh (Pelteobagrus fulvidraco). In yellow catsh, 25%
replacement of sh meal by black soldier y larvae meal produced no
signicant difference in the growth index and immunity index compared
with the control group (Zhang et al., 2014).
Blue tilapia (Oreochromis aureus). Chopped soldier y larvae grown
on hen manure fed to blue tilapia catsh alone or in combination with
commercial diets resulted in similar performance (body weight and total
length) as with the control diets and in sh aroma and texture accept-
able to the consumer (Bondari and Sheppard, 1981). In a later experiment,
feeding dry black soldier y larvae as the sole component of the diet did
not provide sufcient DM or CP intake for good growth for tilapia grown
in tanks. However, chopping improved weight gain by 140% and feed ef-
ciency by 28% (Bondari and Sheppard, 1987).
Rainbow trout (Oncorhynchus mykiss). Black soldier y prepupae
meal reared on dairy cattle manure enriched with 25 to 50% trout offal
could be used to replace up to 50% of sh meal protein in trout diets for
8 wk without signicantly affecting sh growth or the sensory quality of
trout llets although a slight (but nonsignicant) reduction in growth was
observed (Sealey et al., 2011). In a 9-wk study, replacing 25% of the sh
meal protein in rainbow trout diets with black soldier y prepupae meal
reared on pig manure did not affect the weight gain and feed conversion
ratio (St-Hilaire et al., 2007a).
Atlantic salmon (Salmo salar). A control diet containing 20% sh
meal was replaced by black soldier y larvae meal at 25, 50, or 100%
sh meal replacement, resulting in similar growth and sensory testing of
llets, greater feed conversion efciency, and an absence of histological
differences (Lock et al., 2014). However, these authors did caution that
the method of preparation of insect could impact performance.
Turbot (Psetta maxima). Juvenile turbots accepted diets containing
33% defatted black y soldier larvae meal (as a replacement of sh meal)
without signicantly affecting feed intake and feed conversion. However,
specic growth rate was less at all of the inclusion rates. Greater inclusion
rates decreased the acceptance of the diet, resulting in reduced feed intake
and growth performance. The presence of chitin might have reduced feed
intake and nutrient availability and therefore reduced growth performance
and nutrient utilization (Kroeckel et al., 2012).
Housey maggot meal and housey pupae meal (Musca domes-
tica). The use of housey maggots as supplements in sh diets has been
mostly studied in Nigeria for tilapia and catsh species.
African catsh (Clarias gariepinus, Heterobranchus longilis, and
hybrids). There have been numerous experiments in Nigeria on the use of
housey maggots in the diets of African catsh, mostly Clarias gariepinus,
Heterobranchus longilis, and hybrids. The results are generally positive,
but the inclusion of maggot meal should be limited to 25 to 30% because
performance tends to decrease when greater inclusion rates are used (Fa-
sakin et al., 2003; Idowu et al., 2003; Madu and Ufodike, 2003; Sogbesan
et al., 2006; Aniebo et al., 2009; Adewolu et al., 2010; Ossey et al., 2012).
Nile tilapia (Oreochromis niloticus). Nile tilapia fed a 4:1 mixture of
wheat bran and live maggots had a better growth performance, specic
growth rate, feed conversion ratio, and survival than sh fed only wheat
bran (Ebenso and Udo, 2003). When maggot meal was included at 15 to
68% in the diet replacing sh meal, best performance and survival were
obtained at 25% inclusion (34% substitution of sh meal), with no ad-
verse effects on the hematology and homeostasis. However, sources of n-6
and n-3 fatty acids should be included in the diet to enhance the fatty acid
prole in sh (Ogunji et al., 2007; Ogunji et al., 2008a,b).
Mealworm (Tenebrio molitor)
African catsh (Clarias gariepinus). Fresh and dried mealworms
have been found to be an acceptable alternate protein source for the Afri-
can catsh. Replacing 40% of sh meal with mealworm meal in isopro-
teic diets resulted in growth performance and feed utilization efciency
similar to that obtained with the control diet, and performance was still
similar at 80% substitution. Catsh fed solely on live mealworms had a
slight depression in growth performance, but sh fed live mealworms in
the morning and commercial catsh pellets in the afternoon grew as good
Table 3. Fatty acid composition of insect lipids (adapted from Makkar et al., 2014).
Constituents in (% fatty acids) Black soldier y larvae1Housey maggot meal Mealworm House cricket Fish oil2
Saturated fatty acids (%)
Lauric, 12:0 21.4 [49.3] (42.6) -0.5 -
Myristic, 14:0 2.9 [6.8] (6.9) 5.5 4.0 0.7 3.7-7.6
Palmitic, 16:0 16.1 [10.5] (11.1) 31.1 21.1 23.4 10.2-20.9
Stearic, 18:0 5.7 [2.78] (1.3) 3.4 2.7 9.8 1.1-4.7
Monosaturated fatty acids (%)
Palmitoleic, 16:1n-7 [3.5] 13.4 4.0 1.3 8.7-12.5
Oleic, 18: 1n-9 32.1 [11.8] (12.3) 24.8 37.7 23.8 11.4-18.6
Polyunsaturated fatty acids (%)
Linoleic, 18:2n-6 4.5 [3.7] (3.6) 19.8 27.4 38.0 1.1-1.3
Linolenic, 18:3n-3 0.19 [0.08] (0.74) 2.0 1.2 1.2 0.3-0.8
Eicosapentaenoic (EPA), 20:5n-3 0.03 [0] (1.66) - - - 3.7-16.9
Docosahexaenoic (DHA), 22:6n-3 0.006 [0] (0.59) - - - 2-21.9
1Values using cow manure as substrate. Round parentheses are the values obtained on using 50% of cow manure and 50% of sh offal as substrate. Square parentheses are
values obtained on swine manure as substrate.
2Adapted from Sauvant et al., 2004.
40 Animal Frontiers

as or better than sh fed the commercial diet. Live and dried mealworms
were found to be highly palatable. Catsh fed mealworm-based diets had
signicantly more lipids in their carcass (Ng et al., 2001).
Gilthead sea bream (Sparus aurata). In gilthead sea bream juveniles
fed diets containing mealworm meal replacing 25 or 50% of sh meal
protein, 25% substitution did not affect weight gain and nal weight nega-
tively, while 50% substitution induced growth reduction and less specic
growth rate, feed conversion efciency, and protein efciency ratio. The
whole body proximate composition was unchanged (Piccolo et al., 2014).
Rainbow trout (Oncorhynchus mykiss). Mealworm added to a diet
(containing 45% CP) at levels of 25 and 50% by weight (as a replacement
of sh meal) showed that it could be included at up to 50% without reduc-
ing growth performance (Gasco et al., 2014a).
European sea bass (Dicentrarchus labrax). In European sea bass,
including up to 25% of mealworm meal in isoproteic diets as a replace-
ment of sh meal had no adverse effects on weight gain. Inclusion at 50%
reduced growth, specic growth rate, and feed consumption ratio slightly
but not protein efciency ratio, feed consumption, and body composition.
Mealworm inclusion inuenced the fatty acid composition of body lipids
(Gasco et al., 2014b).
Locust Meal, Locusts, Grasshoppers, and Crickets
African catsh (Clarias gariepinus). Desert locust meal (Schisto-
cerca gregaria) could replace up to 25% dietary protein in C. gariepi-
nus juveniles without signicant reduction in growth. Chitin may have
contributed to reduced performance when greater rates were used (Balo-
gun, 2011). Meal of adult variegated grasshopper (Zonocerus variegatus)
could replace up to 25% sh meal in the diets of C. gariepinus ngerlings
without any adverse effect on growth and nutrient utilization at the same
protein level in the diet. Greater inclusion rates decreased digestibility and
performance (Alegbeleye et al., 2012).
Walking catsh (Clarias batrachus). Several studies have investi-
gated the effects of feeding dried Indian grasshoppers (Poekilocerus pic-
tus) on the histological and physiological parameters of walking catsh. A
91-d feeding of dried grasshoppers had no adverse effect on hematologi-
cal parameters but resulted in a little shrinkage in the gills as well as a
reduction in ovarian steroidogenesis, which may reduce fertility (Johri et
al., 2010; Johri et al., 2011a,b).
Nile tilapia (Oreochromis niloticus). Migratory locust meal (Locusta
migratoria) could replace sh meal up to 25% in isoproteic diets of Nile
tilapia ngerlings without an adverse effect on the nutrient digestibility,
growth performance, and hematological parameters (Abanikannda, 2012;
Emehinaiye, 2012).
Silkworm Pupae Meal (Bombyx mori)
Carps. In the common carp (Cyprinus carpio), it was possible to re-
place 100% of sh meal protein with non-defatted silkworm pupae meal
with no adverse effect on growth and feed conversion (Rahman et al.,
1996; Nandeesha et al., 1990). Silkworm pupae meal could be safely used
up to 50% in the diet without adversely affecting growth and esh quality
(Nandeesha et al., 2000). In a comparison between silkworm pupae meal
and alfalfa or mulberry leaf meals, feed conversion efciency, nutrient di-
gestibility, and nutrient retention were better for diets based on silkworm
meal than for diets based on plant leaf meals (Swamy and Devaraj, 1994).
In a polyculture system based on Indian carp (Catla catla), mrigal
carp (Cirrhinus mrigala), rohu (Labeo rohita), and silver carp (Hypoph-
thalmychthys molitrix), fermented silkworm pupae silage (replacing sh
meal) included in formulated diets gave better survival rate, feed conver-
sion ratio, and specic growth rate than untreated fresh silkworm pupae
paste or sh meal (Rangacharyulu et al., 2003). In rohu, non-defatted silk-
worm pupae and defatted silkworm pupae resulted in signicantly greater
protein digestibility values than sh meal (Hossain et al., 1997).
Silver barb (Barbonymus gonionotus). In silver barb ngerlings,
highest growth performance was observed with a diet where silkworm
pupae meal replaced 38% of total dietary protein (Mahata et al., 1994).
Mahseer (Tor khudree). Mahseer ngerlings fed a diet containing
50% defatted silkworm pupae at 5% of body weight had a better growth
and survival than ngerlings fed no or reduced amounts of silkworm pu-
pae (Shyama and Keshavanath, 1993).
Mozambique tilapia (Oreochromis mossambicus). Mozambique tila-
pias could utilize the protein of both defatted and non-defatted silkworm meal
with a high apparent protein digestibility of 85 to 86% (Hossain et al., 1992).
Larvae of the black soldier y. Mealworms.
Dennis Kress Peter Halasz
Apr. 2015, Vol. 5, No. 2 41

Asian stinging catsh (Heteropneustes fossilis). Silkworm pupae meal
could replace sh meal at up to 75% protein substitution in Asian stinging
catsh diets without adverse effect on growth (Hossain et al., 1993).
Walking catsh (Clarias batrachus). Non-defatted silkworm pupae
meal was found to be a suitable sh meal substitute in diets for walking
catsh. Digestibility of the CP in silkworm meal was found to be similar
to that in sh meal (Borthakur and Sarma, 1998a). Walking catsh n-
gerlings fed silkworm meal had slightly lower specic growth rate and
poorer feed conversion ratio (2.81 vs. 2.45) than ngerlings fed on sh
meal (Borthakur and Sarma, 1998b).
Chum salmon (Oncorhynchus keta). Chum salmon fry fed over 6-wk
diets supplemented with 5% silkworm pupae meal at the expense of sh
meal did not show improvement in growth rate and protein content although
silkworm supplementation enhanced feed efciency (Akiyama et al., 1984).
Japanese sea bass (Lateolabrax japonicus). In Japanese sea bass, the
energy digestibility (73%) of non-defatted silkworm pupae meal was less
than that of poultry by-product meal, feather meal, blood meal, and soy-
bean meal but comparable to that of meat and bone meal. Crude protein
digestibility (85%) was also less than that of poultry by-product meal,
blood meal, and soybean meal but was comparable with that of feather
meal and greater than that of meat and bone meal (Ji et al., 2010).
Conclusion
The insect species presented in this review have potential for use as a
source of protein in the diets of farmed sh. Insects are valuable ingredi-
ents rich in protein, lipids, and energy. Numerous trials with carnivorous,
omnivorous, and herbivorous sh have demonstrated that insects can be
successfully included in sh diets as a substitute for sh meal although
there have been more studies on omnivorous species than on carnivorous
ones. Most trials recommend replacement rates less than 25 to 30%. In
some cases, greater rates and even total substitution have been found tech-
nically or economically feasible.
Use of insects for the feeding of farmed sh faces several challenges
from a nutritional perspective. One is the composition of insects and thus
their nutritional value, which is highly dependent on the species, stage of
development, and substrate used to feed the insects. Protein, lipid, and min-
eral composition are all highly variable, even within a taxon at the same
development stage. For instance, the lipid concentration reported in the lit-
erature ranges from 15 to 35% for black soldier y larvae and from 9 to 26%
for housey maggots (DM basis). Such a wide variation is a challenge when
formulating feeds at an industrial scale although recent developments in on-
line estimation of chemical composition using near infrared spectroscopy
(NIRS) could theoretically assist the industry in addressing this challenge.
Another caveat is that none of the species reviewed here can be considered
as a perfect substitute to sh meal. Diptera larvae are most similar to sh
meal in terms of amino acid composition and protein digestibility, but all
insects reviewed in this paper except silkworm pupae have lesser concentra-
tions of sulfur amino acids than sh meal. The absence of EPA and DHA
in the fatty acid prole of insects is also a limitation to their inclusion in
marine sh diets. Depending on the insect and sh species, supplementation
with other sources of amino acids or fatty acids will therefore be required
for optimal growth and sh quality. It is also possible to change insect com-
position through manipulation of their diets.
Before insects can be used for the industrial production of sh feed,
research and development are needed in the following areas.
1. The feasibility of scaling up insect production into an economically
viable business able to provide insects in industrial quantities
needs to be investigated beyond experimental or pilot units. This
includes the development of cost-effective insect diets and the
engineering of specic infrastructures, including the automation
of rearing to reduce labor costs. For insects to be competitive
with the traditional protein sources, they must have distinctive
advantages in terms of nutritional value and price and should be
available year-round in well-dened and consistent qualities.
2. Further work is required on the nutritional value of insects
for sh feeding, and particularly for carnivorous sh: factors
inuencing the chemical composition as well as nutrient and
energy bioavailability; dietary manipulation of the proles of
amino acids, fatty acids, and minerals; processes (such as defatting
and pelleting); palatability and feeding preferences of sh; and
adaptation of sh to insect-based diets.
Grasshopper. Silkworms.
Stefanlend Fastily
42 Animal Frontiers

3. Because one of the main benets of insects is their ability to turn
biowastes into valuable organic matter, sanitation procedures need
to be dened for the safe use of substrate to obtain insects that are
free of diseases and undesirable substances.
4. There is a need to develop a regulatory framework and legislations
for use of insects as animal feed and to improve risk assessment
methodologies.
5. Studies on the impact of feeding insects on the safety, quality, and
social acceptance of shery products obtained on feeding insects
should be conducted.
6. Life cycle assessments of insect production compared with that of
other feed protein production such as sh meal and oilseed meals
should be conducted.
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About the Authors
Valérie Heuzé joined AFZ in 2009. She
completed her engineering studies at
GemblouxAgroBioTech (formerly Fac-
ulté des Sciences Agronomiques de Gem-
bloux, Belgium) in 1992 as a specialist in
agronomy. Since then, she has occupied
different positions at AgroParistech, Re-
ims Management School as a lifelong
learning project manager and teacher. She
also worked as a private agricultural con-
sultant in France and Mali. Since 2009,
she has been in charge of the Feedipedia
programme, an online encyclopedia of
animal feed resources developed by INRA, CIRA, AFZ, and FAO.
Gilles Tran joined AFZ in 1989, after com-
pleting his engineering studies at AgroPar-
isTech as a specialist in animal produc-
tions. Since then, he has been in charge of
the French Feed Database, a national feed
information system. He has participated in
numerous public and private projects con-
cerning feed research and feed information
systems. In 2002–2004, he was in charge
of the co-ordination of the INRA / AFZ
Tables of composition and nutritional val-
ues of feed ingredients. Since 2009, he has
been in charge of the Feedipedia project,
an online encyclopedia of animal feed resources developed by INRA, CIRA,
AFZ, and FAO.
Correspondence: gilles.tran@zootechnie.fr.
Harinder P.S. Makkar has worked as an
animal production ofcer at FAO, Rome
since 2010. Before joining FAO, he was
Mercator Professor at the University of
Hohenheim, Stuttgart, Germany. He has
published more than 250 research papers.
He obtained his Ph.D. from University
of Nottingham, UK and habilitation from
University of Hohenheim. He also worked
at the International Atomic Energy Agen-
cy, Vienna for 7 yr. He has been awarded
honorary professorships by Universities in
China and Mongolia and has been a fellow
of Commonwealth Association, UK; Humboldt Foundation, Germany; and
Japanese Society for the promotion of Science, Japan.
44 Animal Frontiers