Friedrich Ladich

• University of Vienna

My research in fish bioacoustics started in the mid-1980s and comprised the diversity in sound-generating mechanisms and sound production in various contexts such as dyadic contests. I worked on European freshwater and marine fish, but mainly on tropical fish from Southeast Asia (gouramis) and the Amazonian River system (pimelodid, doradid catfishe...

In most vocal fish species, females possess smaller sound‐generating organs and vocalize less than males. In certain cases females lack sonic organs, in others differences between sexes are unknown. This study analyzes in detail the relationship between sexual dimorphism of sonic organs and the characteristics of agonistic behavior and of sounds re...

Ernst Weber stated in 1819, based on dissections, that the swimbladder in the European wels ( Silurus glanis , Siluridae) and related cyprinids serves as an eardrum and that the ossicles connecting it to the inner ear function as hearing ossicles similar to mammals. In the early 20th century, K. von Frisch showed experimentally that catfishes and c...

An increasing level of anthropogenic underwater noise (shipping, drilling, sonar use, etc .) impairs acoustic orientation and communication in fish by hindering signal transmission or detection. Different noise regimes can reduce the ability to detect sounds of conspecifics due to an upward shift of the hearing threshold, a phenomenon termed maskin...

Songbirds and toothed whales are able to produce different sounds with the left and right part of their sonic organs, a phenomenon termed lateralized sound production. In fishes this phenomenon is poorly known, with lateralization having been observed solely in the channel catfish (Ictalurus punctatus). They produce more sounds with their right pec...

Numerous fishes produce sounds and their transmission and detection may be hindered by increasing levels of anthropogenic noise. We investigated acoustic communication during dyadic contests between male croaking gouramis (Trichopsis vittata, Osphronemidae) in the presence and absence of white noise. We hypothesised that fish modify acoustic signal...

Modern bony fishes possess a high morphological diversity in the auditory structures and their auditory capabilities. Yet, our knowledge of how the auditory structures such as the otoliths in the inner ears and the swim bladder work together remains elusive. Gathering experimental evidence on the in-situ motion of fish auditory structures while avo...

In teleost fishes, the evolution of hearing enhancement and corresponding auditory structures remains largely elusive. We know little about the selective pressures acting on the evolution of improved hearing. Cichlids are marked by great species diversity; they have adapted to a variety of ecological niches, including different ecoacoustical condit...

Predation is a major ecological constraint shaping behaviour and communication in animals. Several fish species are known to modify their foraging, agonistic and reproductive behaviour in the presence of predators. However, close to nothing is known about how predators affect sound production in fishes. This paper reviews how vocal fish increase th...

Temperature affects various metabolic and physiological processes in ectothermic animals, including auditory systems. The current study investigates the effect of temperature and thermal acclimation time on hearing sensitivities in a eurythermal and a stenothermal fish possessing accessory hearing structures. Using the auditory evoked potential (AE...

Predation is an important ecological constraint that influences communication in animals. Fish respond to predators by adjusting their visual signalling behaviour, but the responses in calling behaviour in the presence of a visually detected predator are largely unknown. We hypothesize that fish will reduce visual and acoustic signalling including...

No PDF available ABSTRACT Modern bony fishes display a high morphological diversity in their auditory structures. Yet, unraveling the sound-induced in situ interaction of the auditory structures has been challenging. Synchrotron radiation-based imaging techniques with high spatial and temporal resolutions now provide a powerful tool to study the fu...

Despite the diversity in fish auditory structures, it remains elusive how otolith morphology and swim bladder-inner ear (= otophysic) connections affect otolith motion and inner ear stimulation. A recent study visualized sound-induced otolith motion; but tank acoustics revealed a complex mixture of sound pressure and particle motion. To separate so...

Sound communication is affected by ambient temperature in ectothermic animals including fishes. The present study examines the effects of temperature on acoustic signaling in a fish species possessing two different sound-generating mechanisms. The Amazonian Pictus catfish Pimelodus pictus produces low-frequency harmonic sounds (swimbladder drumming...

Fishes communicate acoustically under ecological constraints which may modify or hinder signal transmission and detection and may also be risky. This makes it important to know if and to what degree fishes can modify acoustic signalling when key ecological factors—predation pressure, noise and ambient temperature—vary. This paper reviews short‐time...

Otoliths in bony fishes play an important role in the senses of balance and hearing. Otolith mass and shape are, among others, likely to be decisive factors influencing otolith motion and thus ear functioning. Yet our knowledge of how exactly these factors influence otolith motion is incomplete. In addition, experimental studies directly investigat...

Croaking gouramis (genus Trichopsis, Anabantoidei) generate series of two-pulsed bursts (croaks) during agonistic interactions. Sex-specific differences are minor in T. vittata which raises the question whether sexes differ in the other two species. The current study analyses sounds recorded in female T. schalleri, compares the sound characteristic...

Temperature affects peripheral and central mechanisms of signal production and detection in ectothermic animals. This study reviews for the first time the effects of temperature on acoustic communication in fishes and analyses whether changes in sound properties are coupled to changes in auditory sensitivities. Effects of temperature on sound produ...

Regarding the basics of ear structure-function relationships in fish, the actual motion of the solid otolith relative to the underlying sensory epithelium has rarely been investigated. Otolith motion has been characterized based on a few experimental studies and on approaches using mathematical modeling, which have yielded partially conflicting res...

The characteristics of sounds produced by fishes are influenced by several factors such as size. The current study analyses factors affecting structural properties of acoustic signals produced by female croaking gouramis Trichopsis vittata during agonistic interactions. Female sounds (although seldom analysed separately from male sounds) can equall...

Sound propagates much faster and over larger distances in water than in air, mainly because of differences in the density of these media. This raises the question of whether terrestrial (land mammals, birds) and (semi-)aquatic animals (frogs, fishes, cetaceans) differ fundamentally in the way they communicate acoustically. Terrestrial vertebrates p...

Ambient temperature affects peripheral and central mechanisms of signal production and detection in ectothermic animals. The effects of temperature on sound production have been investigated in representatives of at least 8 families of teleosts, namely, piranhas, thorny catfishes, toadfishes, gurnards, sculpins, gobies, croakers, and gouramis, most...

Regarding the basics of ear structure-function relationships in fishes, there is still a substantial lack of knowledge of functional morphology. In particular, the actual motion of the solid otolith relative to the underlying sensory epithelium in the ear has rarely been investigated. To date, analyses of otolith motion have been mainly based on ma...

The ability to detect sound waves is found in all vertebrates independently of whether they inhabit land, water or soil. Fishes, amphibians, reptiles, birds and mammals can utilize this sensory channel for detection of communication signals emitted in the course of various behaviors, and for the detection of acoustic information emitted by prey or...

An astonishing diversity of inner ears and accessory hearing structures (AHS) that can enhance hearing has evolved in fishes. Inner ears mainly differ in the size of the otolith end organs, the shape and orientation of the sensory epithelia, and the orientation patterns of ciliary bundles of sensory hair cells. Despite our profound morphological kn...

Fishes have evolved an astonishing diversity of peripheral (accessory/ancillary) auditory structures to improve hearing based on their ability to transmit oscillations of gas bladder walls to the inner ears. So far it is unclear to what degree the size of the bladder and the linkage to the ear affect hearing in fishes. An interfamilial study in cat...

Fishes have evolved the largest diversity of inner ears among vertebrates. While G. Retzius introduced us to the diversity of the gross morphology of fish ears in the late nineteenth century, it was A. N. Popper who unraveled the large variety of the fine structure during the last four decades. Modifications of the basic inner ear structure—consist...

The sense of hearing plays an important role for fishes to obtain information about their (acoustic) environment (e.g. Popper 2011, Fay 2011). In numerous taxa, ancillary auditory structures like swimbladder modifications evolved, leading to an improved audition (Braun and Grande 2008). Despite a profound knowledge of inner ear diversity and ancill...

The sense of hearing plays an important role for fishes to obtain information about their (acoustic) environment (e.g. Popper 2011, Fay 2011). In numerous taxa, ancillary auditory structures like swimbladder modifications evolved, leading to an improved audition (Braun and Grande 2008). Despite a profound knowledge of inner ear diversity and ancill...

Otolithic end organs in fishes function as accelerometers and are involved in the senses of balance and hearing (e.g. Popper et al. 2005). Otolith mass and shape are likely decisive factors influencing otolith motion, but while it is largely unknown how different shapes affect otolith movement relative to the sensory epithelium (Popper et al. 2005)...

Sound production in female fish has only seldom been mentioned, which is in contrast to the vast literature on male sound production. This lack of information is surprising because sound-generating mechanisms are present in females of (almost) all vocal species. Typically, female sonic organs are smaller than those of the males, for example in batr...

Investigating the potential ability of juvenile fishes to communicate acoustically requires analysing the development of vocalization and hearing . To date, the ontogeny of both processes has been examined in three non-related species, namely the croaking gourami Trichopsis vittata (family Osphronemidae , order Perciformes), the squeaker catfish Sy...

Data on sex-specific differences in sound production, acoustic behaviour and hearing abilities in fishes are rare. Representatives of numerous catfish families are known to produce sounds in agonistic contexts (intraspecific aggression and interspecific disturbance situations) using their pectoral fins. The present study investigates differences in...

This volume examines fish sounds that have a proven signal function, as well as sounds assumed to have evolved for communication purposes. It provides an overview of the mechanisms, evolution and neurobiology behind sound production in fishes, and discusses the role of fish sounds in behavior with a special focus on choice of mate, sex-specific and...

Sound communication comprising the production and detection of acoustic signals is affected by ambient temperature in ectothermic animals. In the present study we investigated the effects of temperature on sound production and characteristics in the croaking gourami Trichopsis vittata, a freshwater fish from Southeast Asia possessing a highly speci...

Bony fishes have evolved a diversity of sound generating mechanisms and produce a variety of sounds. By contrast to sound generating mechanisms, which are lacking in several taxa, all fish species possess inner ears for sound detection. Fishes may also have various accessory structures such as auditory ossicles to improve hearing. The distribution...

Thorny catfishes produce stridulation sounds (SR) using their pectoral fins and drumming sounds (DR) via swimbladder mechanism in distress situations when hand-held in water and in air. Ladich (1997) argued that SR and DR are aimed at different receivers (predators) in different media. The aim of this study was to analyse sounds, compare characteri...

Background In ectothermal animals such as fish, -temperature affects physiological and metabolic processes. This includes sensory organs such as the auditory system. The reported effects of temperature on hearing in eurythermal otophysines are contradictory. We therefore investigated the effect on the auditory system in species representing two dif...

Seahorses are known to produce sounds in different behavioural contexts, but information on the sound production in this fish group is scarce. Here we examined the acoustic behaviour of the longsnout seahorse Hippocampus reidi by analysing sound production when fish were introduced to a new environment and during feeding, handling and courtship. We...

Common carp Cyprinus carpio, stressed by fish handling practices, responded with a decrease in cortisol secretion when temperature was lowered from 20 to 14° C within 3·5 h compared to those kept at 20° C.

Background: Cichlid fishes show considerable diversity in swim bladder morphology. In members of the subfamily Etroplinae, the connection between anterior swim bladder extensions and the inner ears enhances sound transmission and translates into an improved hearing ability. We tested the hypothesis that those swim bladder modifications coincide wi...

Fishes evolved a large diversity of hearing sensitivities. This diversity is linked mainly to differences in the way the inner ear is connected to gas-filled cavities such as the swim bladder. A close connection via accessory hearing structures such as Weberian ossicles results in higher auditory sensitivity or an expansion of the detectable freque...

The ambient noise in aquatic habitats is characterized by a large variety of noise levels and spectral profiles due to various abiotic and biotic factors such as running water, wind, tides, and vocalizing animals. Fish hearing sensitivity declines when exposed to high noise levels or in the presence of masking noise, in particular, in taxa possessi...

A recent survey lists more than 100 papers utilizing the auditory evoked potential (AEP) recording technique for studying hearing in fishes. More than 95 % of these AEP-studies were published after Kenyon et al. introduced a non-invasive electrophysiological approach in 1998 allowing rapid evaluation of hearing and repeated testing of animals. Firs...

Background In most modern bony fishes (teleosts) hearing improvement is often correlated with a close morphological relationship between the swim bladder or other gas-filled cavities and the saccule or more rarely with the utricle. A connection of an accessory hearing structure to the third end organ, the lagena, has not yet been reported. A recent...

Thorny catfishes exhibit large variations in swim bladder morphology. These organs are of different sizes, forms and may have simple or branched diverticula. The swim bladder plays an important role in otophysans because it enhances their hearing sensitivity by transmitting sound pressure fluctuations via ossicles to the inner ear. To investigate i...

Background Hearing thresholds of fishes are typically acquired under laboratory conditions. This does not reflect the situation in natural habitats, where ambient noise may mask their hearing sensitivities. In the current study we investigate hearing in terms of sound pressure (SPL) and particle acceleration levels (PAL) of two cichlid species with...

Several teleost species have evolved anterior extensions of the swim bladder which come close to or directly contact the inner ears. A few comparative studies have shown that these morphological specializations may enhance hearing abilities. This study investigates the diversity of swim bladder morphology in four Asian and African cichlid species a...

Batrachoidids, including the Lusitanian toadfish Halobatrachus didactylus, have become good models for studying acoustic communication as they are unusual strongly vocal species and rely on their hearing abilities to find mates during the breeding season. The major goals of this ongoing study are (1) to verify whether the hearing sensitivity of the...

Fishes, the largest group of living vertebrates, have evolved a unique array of sound-producing (sonic and vocal) organs to produce acoustic signals (vocalizations) in various social contexts. Most fish generate sound by vibrating either the swimbladder or the pectoral girdle with fast-contracting drumming muscles, by rubbing pectoral spines in gro...

Sound production and hearing sensitivity of ectothermic animals are affected by the ambient temperature. This is the first study investigating the influence of temperature on both sound production and on hearing abilities in a fish species, namely the neotropical Striped Raphael catfish Platydoras armatulus. Doradid catfishes produce stridulation s...

The weberian apparatus of otophysine fishes facilitates sound transmission from the swimbladder to the inner ear to increase hearing sensitivity. It has been of great interest to biologists since the 19(th) century. No studies, however, are available on the development of the weberian ossicles and its effect on the development of hearing in catfish...

Catfish possess a high diversity in accessory hearing structures, hearing sensitivities, and sound?generating mechanisms. Nevertheless, the ontogeny of their hearing and sound communication remains unknown. We investigated the development of Weberian ossicles and hearing sensitivity in the African bullhead catfish from postlarval stages up to adult...

Pigmentation disorders such as albinism are occasionally associated with hearing impairments in mammals. Therefore, we wanted to investigate whether such a phenomenon also exists in non-mammalian vertebrates. We measured the hearing abilities of normally pigmented and albinotic specimens of two catfish species, the European wels Silurus glanis (Sil...

Fishes, as broadly defined to include agnathans (jawless fishes), cartilaginous fishes, and bony fishes, are the earliest vertebrates (Fig. 4.1). Because an inner ear is found in the fossil record of the most primitive jawless vertebrates (Forey and Janvier (1994), it is reasonable to assume that the ear, and possibly hearing, arose quite early in...

A recent survey lists more than 100 papers utilizing the auditory evoked potential (AEP) recording technique for studying hearing in fishes. More than 95 % of these AEP-studies were published after Kenyon et al. introduced a non-invasive electrophysiological approach in 1998 allowing rapid evaluation of hearing and repeated testing of animals. Firs...

Several studies on fishes have shown that behaviour and auditory sensitivity are often affected by underwater noise. The current investigation concentrates on noise encountered by fish kept for leisure in aquaria and ponds. Noise spectra showed that all aquarium filters measured created a high amount of low-frequency noise, while the water outflow...

Fishes, the most abundant and diverse group among all vertebrates, exploit the largest number of communication channels. These two volumes explore how fishes use hearing and vision, as well as the vibrational, electric and chemical modalities in their interactions with one another.

Friedrich Ladich is an associate professor at the Department of Behavioural Biology at the University of Vienna, Austria. His research interests focus on acoustic communication in fishes. The work covers sound-generating organs and their neuronal control, the design of acoustic signals, acoustical behavior, the significance of sounds, and the perce...

Many fishes rely on their auditory skills to interpret crucial information about predators and prey, and to communicate intraspecifically. Few studies, however, have examined how complex natural sounds are perceived in fishes. We investigated the representation of conspecific mating and agonistic calls in the auditory system of the Lusitanian toadf...

Cave fish have rarely been investigated with regard to their inner ear morphology, hearing abilities, and acoustic communication. Based on a previous study that revealed morphological differences in the saccular otolith between a cave and two surface populations of Poecilia mexicana, we checked for additional differences in utricular and lagenar ot...

In killer whales or orcas (Orcinus orca) vocal matching appears to be an important aspect of within-group communication, but fish-eating “resident” orcas frequently associate with whales that share little or none of their repertoire. The production of calls belonging to another group's repertoire would allow vocal matching in such contexts and has...

Changes in habitat acoustics over the year can potentially affect fish hearing and orientation to sound, especially in temperate climates. This is the first study where year-round changes in ambient noise in aquatic habitats were assessed. Seven different European fresh-water habitats were chosen for this study. Sound pressure level (SPL) and spect...

A correlative study using similar-sized males of the croaking gourami Trichopsis vittata was carried out to investigate whether sound characteristics influenced winning and if relative fighting ability was assessed by acoustic signals. Pair-wise contests between males were decided using lateral displays (LD) and vocalization in 26 cases, whereas 66...

Agonistic behaviour in the river bullhead C. gobio consists of visual (raising gill covers and fins, lowering the head, darkening) and acoustic (single knock sounds and trains of knock sounds) threat displays, rarely followed by attacks and bites. This study investigates the relationship of vocalizations with size, dominance, territory dimensions a...

Trichopsis vittatus emits high amplitude sounds during agonistic encounters with conspecifics. The sound producing organ is derived from the structural components of the pectoral fins.The study involved muting a sample of subjects by removing two pectoral fin tendons without any further restriction in movements and behaviour. Mute and unaltered mal...

Surveys of ontogenetic development of hearing and sound production in fish are scarce, and the ontogenetic development of acoustic communication has been investigated in only two fish species so far. Studies on the labyrinth fish Trichopsis vittata and the toadfish Halobatrachus didactylus show that the ability to detect conspecific sounds develops...

Fishes show great variability in hearing sensitivity, bandwidth, and the appropriate stimulus component for the inner ear (particle motion or pressure). Here, hearing sensitivities in three vocal marine species belonging to different families were described in terms of sound pressure and particle acceleration. In particular, hearing sensitivity to...

Fishes show great variability in hearing sensitivity, bandwidth, and the appropriate stimulus component for the inner ear (particle motion or pressure). Here, hearing sensitivities in three vocal marine species belonging to different families were described in terms of sound pressure and particle acceleration. In particular, hearing sensitivity to...

The WWF-Natural Marine Reserve of Miramare (Trieste, Italy) is located in a major industrial and vacation area in the Adriatic Sea. Consequently, noise emanating from boating and shipping is an inevitable factor for local fishes. This study investigates the effects of ambient and ship noise on representatives of three vocal fish families with diffe...

The auditory evoked potential (AEP) recording technique has proved to be a very versatile and successful approach in studying auditory sensitivities in fishes. The AEP protocol introduced by Kenyon, Ladich and Yan in 1998 using an air speaker with the fish positioned at the water surface gave auditory thresholds in goldfish very close to behavioura...

Agonistic behaviour and the significance of acoustic threat displays were investigated in juvenile red-finned loaches, Yasuhikotakia modesta. This species produced two different vocalizations during agonistic encounters—clicks and butting sounds. Clicks were produced at some distance from the opponent whereas butting sounds were emitted when one fi...

Anthropogenic noise emanating from ship and boat traffic causes growing concerns because it might hinder acoustic orientation and communication in vocalizing fish species. The Miramare Marine Natural Reserve is located in a coastal area of the Gulf of Trieste (North Adriatic Sea, Italy) characterized by considerable commercial and recreational boat...

Croaking gouramis, Trichopsis vittata (family Osphronemidae), possess enhanced pectoral fin muscles and tendons, enabling the fish to generate series of short or long broadband bursts while beating the fins. Agonistic disputes over territories result in lateral displays during which both sexes produce croaking sounds. During mating, a female approa...

Acoustic displays have been observed in representatives of 30 or more families of bony fishes. Thanks to Art Myrberg’s groundbreaking work, we have insights into the multitude of functions of acoustic signalling in fishes including mate choice, individual and species recognition, reduction of territory intrusions, and interception. Recent studies,...

Fish get crucial information for their survival from their acoustic environment. Therefore, changes in ambient noise as well as temperature over the year potentially impose great challenges for fishes, especially in freshwater habitats in temperate climates. Noise levels vary more in stagnant habitats such as lakes, backwaters, and streams than in...

Sounds were produced by the topmouth minnow Pseudorasbora parva, a common Eurasian cyprinid, during feeding but not during intraspecific interactions. Feeding sounds were short broadband pulses with main energies between 100 and 800 Hz. They varied in their characteristics (number of single sounds per feeding sequence, sound duration and period, an...

Underwater noise pollution is a growing problem in aquatic environments and as such may be a major source of stress for fish. In the present study, we addressed the effects of ship noise and continuous Gaussian noise on adrenal activity in three European freshwater species. Underwater ship noise recorded in the Danube River and two Austrian lakes w...

Acoustic signals emitted by the gudgeon are described and the context of sound production is considered. In aquaria, gudgeons produce creaking sounds of differing duration, which are always built up of single bursts. Each burst is composed of a series of rapidly repeated short pulses. Vocalization is correlated with the level of activity: it increa...

Acoustic signals of Cottus gobio consist of knocking sounds produced as single pulses (48 ms) or as trains of 4–6 pulses (230 ms). Frequencies extend up to 3 kHz, but most sound energy is concentrated between 50 and 500 Hz in both sound types. Cottus gobio is solitary, maintains territories, and defends them by threat display, seldom by biting and...

Fishes have evolved the largest diversity of sonic organs among vertebrates. The main group of sound producing mechanisms is based on the swimbladder. These can be vibrated by intrinsic drumming muscles located in the wall of the swimbladder (toadfishes, searobins), or by extrinsic drumming muscles, which originate on structures such as the skull,...

Fishes have evolved a diversity of sound-generating organs. These include vibrating the swimbladder and pectoral girdle by rapidly contracting muscles or rubbing bony elements against each other (stridulation) and plucking enhanced tendons. While the former mechanisms produce low-frequency, often harmonic signals (< 500 Hz), the latter usually gene...

Fishes have evolved diverse mechanisms to generate sound. These include rubbing of bony elements against each other (stridulation), vibrating swim bladders or pectoral girdles via rapidly contracting muscles, and plucking enhanced tendons of pectoral fins. While stridulatory or plucking mechanisms produce wideband pulsed sounds with frequencies ext...

Catfishes have evolved a diversity of swimbladder muscles serving in the generation of different sounds and probably other acoustic functions. In order to find out if anatomical and acoustical differences are parallelled by fine structural differences, I examined the sonic muscles of the doradid Platydoras and the pimelodid Pimelodus by gross disse...

Sound production during reproductive behaviour, dyadic encounters and distress situations was investigated in the callichthyid catfish Corydoras paleatus. Sounds were broad-band, pulsed, acoustic signals produced during abduction of the pectoral spines. Only males emitted trains of sounds during courting and trains of sounds of shorter duration dur...