Surgical repair of mandibular symphyseal fractures in three silver arowana (Osteoglossum bicirrhosum) using interfragmentary wire.

Three silver arowana (Osteoglossum bicirrhosum) were presented with unstable fractures of the mandibular symphyses. Surgical repair was performed to reduce and stabilize the fractures using interfragmentary wire. The fish returned to light feeding at 2 days and normal feeding at 5 days postsurgery. The wires were removed at 6 wk postsurgery with good alignment of the mandibular symphyses and stable fracture sites. There had been no further complications at the time of writing 18 wk postsurgery.

Injuries and deformities in fish: their potential impacts upon aquacultural production and welfare.

Fish can be the recipients of numerous injuries that are potentially deleterious to aquacultural production performance and welfare. This review will employ a systematic approach that classifies injuries in relation to specific anatomical areas of the fish and will evaluate the effects of injury upon production and welfare. The selected areas include the (1) mouth, (2) eye, (3) epidermis and (4) fins. These areas cover a large number of external anatomical features that can be injured during aquacultural procedures and husbandry practices. In particular, these injuries can be diagnosed on live fish, in a farm environment. For each anatomical feature, this review addresses (a) its structure and function and (b) defines key injuries that can affect the fish from a production and a welfare perspective. Particular attention is then given to (c) defining known and potential aquacultural risk factors before (d) identifying and outlining potential short- and long-term farming practices and mitigation strategies to reduce the incidence and prevalence of these injuries. The review then concludes with an analysis of potential synergies between risk factors the type of injury, in addition to identifying potential synergies in mitigation strategies. The paper covers both aquaculture and capture-based aquaculture.

A Comparative Perspective on Brain Regeneration in Amphibians and Teleost Fish.

Regeneration of lost cells in the central nervous system, especially the brain, is present to varying degrees in different species. In mammals, neuronal cell death often leads to glial cell hypertrophy, restricted proliferation, and formation of a gliotic scar, which prevents neuronal regeneration. Conversely, amphibians such as frogs and salamanders and teleost fish possess the astonishing capacity to regenerate lost cells in several regions of their brains. While frogs lose their regenerative abilities after metamorphosis, teleost fish and salamanders are known to possess regenerative competence even throughout adulthood. In the last decades, substantial progress has been made in our understanding of the cellular and molecular mechanisms of brain regeneration in amphibians and fish. But how similar are the means of brain regeneration in these different species? In this review, we provide an overview of common and distinct aspects of brain regeneration in frog, salamander, and teleost fish species: from the origin of regenerated cells to the functional recovery of behaviors.

Injury-mediated decrease in locomotor performance increases predation risk in schooling fish.

The costs and benefits of group living often depend on the spatial position of individuals within groups and the ability of individuals to occupy preferred positions. For example, models of predation events for moving prey groups predict higher mortality risk for individuals at the periphery and front of groups. We investigated these predictions in sardine (Sardinella aurita) schools under attack from group hunting sailfish (Istiophorus platypterus) in the open ocean. Sailfish approached sardine schools about equally often from the front and rear, but prior to attack there was a chasing period in which sardines attempted to swim away from the predator. Consequently, all sailfish attacks were directed at the rear and peripheral positions of the school, resulting in higher predation risk for individuals at these positions. During attacks, sailfish slash at sardines with their bill causing prey injury including scale removal and tissue damage. Sardines injured in previous attacks were more often found in the rear half of the school than in the front half. Moreover, injured fish had lower tail-beat frequencies and lagged behind uninjured fish. Injuries inflicted by sailfish bills may, therefore, hinder prey swimming speed and drive spatial sorting in prey schools through passive self-assortment. We found only partial support for the theoretical predictions from current predator-prey models, highlighting the importance of incorporating more realistic predator-prey dynamics into these models.This article is part of the themed issue 'Physiological determinants of social behaviour in animals'.

Use of navigation channels by Lake Sturgeon: Does channelization increase vulnerability of fish to ship strikes?

Channelization for navigation and flood control has altered the hydrology and bathymetry of many large rivers with unknown consequences for fish species that undergo riverine migrations. In this study, we investigated whether altered flow distributions and bathymetry associated with channelization attracted migrating Lake Sturgeon (Acipenser fulvescens) into commercial navigation channels, potentially increasing their exposure to ship strikes. To address this question, we quantified and compared Lake Sturgeon selection for navigation channels vs. alternative pathways in two multi-channel rivers differentially affected by channelization, but free of barriers to sturgeon movement. Acoustic telemetry was used to quantify Lake Sturgeon movements. Under the assumption that Lake Sturgeon navigate by following primary flow paths, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River were expected to choose navigation channels over alternative pathways and to exhibit greater selection for navigation channels than conspecifics in the less-channelized lower St. Clair River. Consistent with these predictions, acoustic-tagged Lake Sturgeon in the more-channelized lower Detroit River selected the higher-flow and deeper navigation channels over alternative migration pathways, whereas in the less-channelized lower St. Clair River, individuals primarily used pathways alternative to navigation channels. Lake Sturgeon selection for navigation channels as migratory pathways also was significantly higher in the more-channelized lower Detroit River than in the less-channelized lower St. Clair River. We speculated that use of navigation channels over alternative pathways would increase the spatial overlap of commercial vessels and migrating Lake Sturgeon, potentially enhancing their vulnerability to ship strikes. Results of our study thus demonstrated an association between channelization and the path use of migrating Lake Sturgeon that could prove important for predicting sturgeon-vessel interactions in navigable rivers as well as for understanding how fish interact with their habitat in landscapes altered by human activity.

A comparison of hematology, plasma chemistry, and injuries in Hickory shad (Alosa mediocris) captured by electrofishing or angling during a spawning run.

BACKGROUND: Declines in Hickory shad (Alosa mediocris) populations in Chesapeake Bay have prompted efforts at captive propagation of wild broodfish for stock enhancement and research. OBJECTIVE: The objectives of this study were to evaluate injuries sustained, and immediate and delayed (24 hours) effects on blood variables related to 2 fish capturing methods (electrofishing [EF] and angling). METHODS: Blood specimens were collected from fish immediately following capture by EF and angling (n = 40 per sex and capture method) from the Susquehanna River (MD, USA). Additional fish (n = 25 per sex and capture method) were collected on the same day, placed in holding tanks and bled 24 hours following capture. Blood data that were non-Gaussian in distribution were transformed (Box-Cox), and effects of sex, method of capture, and holding time were tested using ANOVA with general linear models. Fish were evaluated for injuries by necropsy and radiography. RESULTS: Sex-specific differences were observed for RBC, HGB, PCV, MCH, MCHC, total proteins (TP), globulins, glucose, calcium, AST, CK, and lactate, while RBC, HGB, PCV, MCV, MCH, MCHC, TP, albumin, globulins, glucose, potassium, sodium, AST, CK, and lactate differed significantly by fish capturing method. Electrofishing may have induced greater disruption in blood variables, but mortality (4%) was not significantly different compared to angling. CONCLUSIONS: Electrofishing for Hickory shad using a constant DC voltage resulted in numerous hematologic and biochemical changes, with no additional injuries or deaths compared to angling. Capture method must be considered when evaluating fish condition, and blood variables should be partitioned by sex during spawning season.

Migration of the curimbatá Prochilodus lineatus (Valenciennes, 1836) (Pisces, Prochilodontidae) at the waterfall "Cachoeira de Emas" of the Mogi-Guaçu river--São Paulo, Brazil.

In this paper, we counted the ascending curimbatás at the fish ladder at the Cachoeira de Emas from October, 1992 to September, 1993 in one whole day (24 h period) per month at different observation points in the dam for 5 min every hour. Most of the fish (80%) were counted not in the fish ladder itself, but in two adjacent spillways at its left, perhaps due to the comparatively increased flow as they are narrower than the ladder. The bulk of the migration occurred in September/October. We inspected the degree of injury of the fish in order to examine the hypothesis that larger fish are less injured, however no conclusion was reached. The degree of injury varied between different points and in different months of the year.

Effects of Exposure to the Sound from Seismic Airguns on Pallid Sturgeon and Paddlefish.

This study examined the effects of exposure to a single acoustic pulse from a seismic airgun array on caged endangered pallid sturgeon (Scaphirhynchus albus) and on paddlefish (Polyodon spathula) in Lake Sakakawea (North Dakota, USA). The experiment was designed to detect the onset of physiological responses including minor to mortal injuries. Experimental fish were held in cages as close as 1 to 3 m from the guns where peak negative sound pressure levels (Peak- SPL) reached 231 dB re 1 µPa (205 dB re 1 µPa2·s sound exposure level [SEL]). Additional cages were placed at greater distances in an attempt to develop a dose-response relationship. Treatment and control fish were then monitored for seven days, euthanized, and necropsied to determine injuries. Necropsy results indicated that the probability of delayed mortality associated with pulse pressure following the seven day monitoring period was the same for exposed and control fish of both species. Exposure to a single pulse from a small air gun array (10,160 cm3) was not lethal for pallid sturgeon and paddlefish. However, the risks from exposure to multiple sounds and to sound exposure levels that exceed those reported here remain to be examined.

Parasitic lesions in fish in the Federal District, Brazil

Brazil has a vast territory and favorable climatic conditions that allow the cultivation of freshwater fish. The intensification of the productive system can cause an imbalance in the aquatic environment as a result of poor water quality, nutritional deficiencies and infectious or parasitic diseases. The laboratory diagnosis and the determination of the prevalence of the main lesions, which occur in a certain region, help to guide towards the etiological diagnosis. This study aimed to describe the main parasitic lesions in fish in the routine at the Veterinary Pathology Laboratory of the Universidade de Brasília (UnB). All records of fish with parasitic lesions were recovered. Those cases in which there was an intralesional parasite and which presented lesions compatible with the parasite were included. The screening of ectoparasites was done by scraping the superficial mucus from the gills and skin. Organ sections were routinely processed for histopathologyand stained with hematoxylin-eosin (HE). In some records, parasitological identification was carried. The information was divided into the species of the affected fish, epidemiology of the outbreak (water quality, temperature, type of breeding), lesion distribution, etiology and macroscopic and microscopic changes. The resulting data was organized in absolute frequency and percentage. In this study, 22 cases were counted, between individual deaths and outbreaks, totaling 83 necropsied teleost fish. Inflammatory changes of parasitic origin were seen in 13/22 (59%) of the cases had lesions of parasitic origin. Skin lesions and gills were the most relevant. Macroscopically, red areas or spots of hyperemia or hemorrhage on the body surface were the most prevalent findings. Under microscopy, proliferative gill inflammation was the most relevant diagnosis. Pscinoodinium pilullare (Dinoflagellida), Ichthyophthirius multifiliis (Ciliophora), and monogenetic worms (Monogenea) were the main parasites found. Trichodina sp. (Ciliophora), Ichtyobodo sp. (Kinetoplastida), Amoebas, and Chilodonella sp. (Ciliophora), were seen in fewer numbers. An unusual case suggestive of parasitism by Eustrongylides sp. (Nematoda), in a pirá-brasília (Simpsonichthys boitonei), specimen has been recorded. The diagnoses were based on epidemiology, anatomopathological and parasitological findings. The most frequent and significantly lethal lesion in the study was proliferative and / or hyperplastic branchitis. Proliferative branchitis with lamellar epithelial hyperplasia (LEH) is a response to some type of chemical or mechanical injury to the gill epithelium in order to protect the capillaries from further damage or microbial penetration. However, it also increases the diffusion distance between capillaries and the environment and, therefore, hinders breathing, excretory and osmoregulatory functions. Protozoan infections and monogenetic worms in general generated LEH and skin lesions of mechanical origin. Secondary bacterial infection, were observed in this parasitosis determining the cause of death of the fish. Its pathogenicity comes from the lesions caused by the colonization and histophagy of the epithelial surfaces, mainly gills and skin, causing epithelial proliferation, lamellar cell fusion, epithelial cell degeneration and necrosis forming several ulcers in the epithelium after the release of mature trophies. The pathogenesis of parasitism by Eustrongylides spp. is considerable when there is a large quantity of these larvae that can cause intestinal obstruction, rupture and compression of viscera, of greater importance in small fish. The main parasites of necropsied fish were protozoa and monogenetic worms, which mainly cause branquitis and dermatitis in varying grades.(AU)

Surface characters and extracellular toxins involved in the pathogenesis of Aeromonas hydrophila.

A small number of serotypically distinct strains of A. hydrophila obtained from diseased freshwater fish were examined for their pathogenic properties comprising of cell surface characteristics and extracellular toxins. Test strains exhibited homogeneity in their cell surface characteristics despite being serologically heterogeneous. Studies on extracellular biological activities revealed qualitative and quantitative differences in production of toxins, probably explaining their antigenic diversity. Three distinct proteases, namely heat stable metallo protease, heat labile serine protease and heat labile metallo protease were identified from the strains.

Diseases and injuries associated with mortality of hatchery reared Baltic cod (Gadus morhua L.) larvae.

A cod hatching plant was established in 1992 on the island of Bornholm in the Baltic Sea in order to elucidate the possibilities for restocking of cod fry in this brackishwater system. The disease prevalence in 3 batches of hatchery-reared yolksac larvae from the Baltic cod (Gadus morhua L.) was monitored during the posthatch period. High prevalences of bacteriosis/mycosis, lordosis/scoliosis, injuries and protozoan endoparasitism were recorded. Vibrio sp. and Vibrio anguillarum serovar 04, 06, 08 in addition to nontypable strains and saprolegniaceous fungi were isolated from the larvae. The dinoflagellate-like endoparasites were located in the yolksac of the cod larvae.

Wound management in teleost fish: biology of the healing process, evaluation, and treatment.

Wound healing, although similar to terrestrial vertebrates, occurs faster in fish species in a proper aquatic environment. Wound management must involve identification and correction of potential noninfectious and/or infectious causes of disease. Wound evaluation includes assessment of the wound as well as systematic examination of the patient, water quality conditions, and husbandry practices. Diagnostic evaluation should, at a minimum, include physical examination, skin/cornea (if indicated) scraping, and lesions cultures. The clinician should also consider full thickness wound biopsies, gill and fin biopsies, blood collection, and radiographs for systemic evaluation as well. Local wound management should follow basic principles of wound care including cleaning and lavage, debridement, primary closure if indicated, and local and/or systemic antiinfectives. Monofilament absorbable or nonabsorbable sutures are commonly used for primary closure of wounds. Diagnostic results, patient and client compliance, and economic impact should guide systemic methods of treatment for wound care. Options for systemic therapy include oral or gavage, parenteral, bath, or prolonged immersion treatments. With bath or prolonged immersion therapies, aquatic systems must be properly prepared for treatment. Treatment of identified pathogens, proper water quality and husbandry, supportive care and nutrition must all be provided to promote an ideal wound healing environment for the teleost fish.

[Injury to fish by turbine plants]. / Schädigung von Fischen durch Turbinenanlagen.

In the Federal Republic of Germany, 7% of the electric power is generated by Hydro-electric plants. A water current is used to drive a turbine, to generate electricity. Fish are passively drawn into the turbines by the water flow, or they migrate actively downstream (eels). Fish then may be injured or even killed. The national Countries' Fishery Acts are not sufficient to compel the prevention of fish gaining access to the turbines. To compensate for losses to the fishery, the owners of Hydro power plants can re-stock their water supplies. Superior to the Fishery Acts of the various Countries is the Federal Animal Protection Law. According to its principle, it is not allowed to cause pain, suffering or damage to an animal without a reasonable cause. It cannot be the intention of either the Fishery Acts or the Animal Protection Law to compensate losses in the fish population by re-stocking. On the contrary, the damage has to be prevented in advance. A suitable means to achieve this is the combination of electrified barriers with a bypass for fish.

[Electrofishing from animal welfare aspects]. / Elektrofischerei unter Tierschutzaspekten.

Through improper application of electrofishing techniques fish may be harmed severely. The injuries can range from inner bleeding to broken vertebrae. Due to these possible injuries each electrofishing procedure requires approval of the fisheries authorities. Only persons with a special license are allowed to fish with electricity. The fisheries authorities only approve electrofishing for reasons stated in the fisheries laws. If an application to fish with electricity is approved, the permission is restricted to certain persons, certain equipment units, certain stretches of water and clearly outlined goals. Damages to fish can be reduced to a minimum by the strict regulations of the fisheries authorities and by the training of the fishermen.

Injuries from non-retention in gillnet fisheries suppress reproductive maturation in escaped fish.

Exploitation of fisheries resources has unintended consequences, not only in the bycatch and discard of non-target organisms, but also in damage to targeted fish that are injured by gear but not landed (non-retention). Delayed mortality due to non-retention represents lost reproductive potential in exploited stocks, while not contributing to harvest. Our study examined the physiological mechanisms by which delayed mortality occurs and the extent to which injuries related to disentanglement from commercial gear compromise reproductive success in spawning stocks of Pacific salmon (Oncorhynchus spp.). We found evidence for elevated stress in fish injured via non-retention in gillnet fisheries. Plasma cortisol levels correlated with the severity of disentanglement injury and were elevated in fish that developed infections related to disentanglement injuries. We also analyzed sex steroid concentrations in females (estradiol-17ß and 17,20ß-dihydroxy-4-pregnen-3-one) to determine whether non-retention impairs reproductive potential in escaped individuals. We demonstrate evidence for delayed or inhibited maturation in fish with disentanglement injuries. These findings have important implications for effective conservation and management of exploited fish stocks and suggest means to improve spawning success in such stocks if retention in commercial fisheries is improved and incidental mortality reduced.

Report of 15 injuries caused by lionfish (pterois volitans) in aquarists in Brazil: a critical assessment of the severity of envenomations

Lionfish are venomous fish that belong to the Scorpaenidae family. Individuals of this family and those of the Synanceiidae family comprise most of the existing venomous fish in the world. Lionfish are originally found in the Indo-Pacific, but they have received special attention in the last years for their dissemination in the Atlantic Ocean, with the emergence of large populations in the USA, Caribbean and South America. Because of its beauty, this fish has always been present in private and commercial aquariums around the world. Herein, we describe 15 envenomations in aquarists registered in a period of eighteen years (1997-2014). The stings caused excruciating pain and marked inflammation, with local erythema, edema, heat, paleness and cyanosis. In one case, it was possible to observe vesicles and blisters. There were no skin necroses or marked systemic manifestations. We discuss the possible coming of the fish to South America and the circumstances and clinical impact of the envenomations.(AU)

Tempo de indução e recuperação à anestesia do eugenol para patinga (Piaractus brachypomus) / Eugenol anesthesia induction and recovery time for (Piaractus brachypomus) / Tiempo de inducción y recuperación a la anestesia de eugenol en morocoto (Piaractus brachypomus)

Este trabalho tem como finalidade avaliar o uso do eugenol como anestésico para a patinga (Piaractus brachypomus), mensurando o tempo de indução à anestesia e recuperação. Foram mensurados o tempo de indução e recuperação à anestesia em diferentes concentrações de eugenol e glicose plasmática. Os resultados foram analisados segundo um delineamento inteiramente casualisado (DIC) com seis tratamentos (controle, 25, 35, 50, 75 e 150 L-1 de eugenol) e dez repeti- ções cada. As análises de variância (ANOVA) e as médias foram comparadas pelo teste de Tukey. Concentrações acima de 150mg.L-¹ apresentaram mortalidade de 100% da população. Os tempos de indução à anestesia profunda registrada para as concentrações de 50 e 75mg L-1 foram que apresentaram menores tempos de sedação. Observa-se que o tempo de recuperação patinganas doses de 50mg.L-¹ foi de 93 seg. a dose de 25mg.L-1 de eugenol foi a única que obteve diminuição nos níveis de glicose plasmática, o que pode ser um indício de utilização de pequenas doses deste no manejo da patinga. Conclui-se que o eugenol é um anestésico adequado para juvenis patinga com peso de 256,6±73,18g. Podendo utilizado em concentrações de 50mg. L-1 de eugenol...

This paper aims to standardize the use of eugenol as an anesthetic for the patinga (Piaractus brachypomus), measuring the time for anesthesia induction and recovery. Induction and recovery times to anesthesia were measured in different concentrations of eugenol and plasma glucose. The results were analyzed according to a completely randomized design (CRD) with six treatments (control, 25, 35, 50, 75 and 150 L-1 of eugenol) and ten repetitions each. The analysis of variance (ANOVA) and averages were compared by Tukey test. Concentrations above 150 mg.L-¹ presented 100% mortality of the population. The deep anesthesia induction times recorded for concentrations of 50 and 75 mg L-1 were the ones presenting the shortest sedation times. It can be observed that the patinga recovery time for 50mg.L-1 doses was 93 seconds. The 25mg.L-1 dose of eugenol was the only dose obtaining a decrease in plasma glucose levels which can be an indication to the use of small doses for the management of patinga. It can also be concluded that eugenol is a suitable anesthetic for patinga weighing 256.6 ± 73.18 g, and it can be used at concentrations of 50mg. L-1 eugenol...

Este estudio ha tenido como objetivo evaluar el uso de eugenol como anestésico para el morocoto Piaractus brachypomus, midiendo el tiempo de inducción a la anestesia y recuperación. Fueron medidos el tiempo de inducción y recuperación a la anestesia en diferentes concentraciones de eugenol y la glucosa plasmática. Los resultados fueron analizados según un delineamiento enteramente casualizado con seis tratamientos (control, 25, 35, 50, 75 y 150 L-1 de eugenol) y 10 (diez) repeticiones cada uno. El análisis de varianza (ANOVA) y los promedios se compararon por prueba Tukey. Concentraciones superiores a 150 mg.L-¹ presentaron mortalidad de 100% de la población. Los tiempos de inducción a la anestesia profunda registrada para las concentraciones de 50 y 75 mg L-1 fueron las que presentaron menores tiempos de sedación. Se observa que el tiempo de recuperación de morocotos con dosis de 50 mg.L-1 fue de 93 seg. La dosis de 25 mg.L-1 de eugenol fue la única que obtuvo disminución en los niveles de glucosa plasmática, lo que puede ser un indicio de utilización de dosis pequeñas de esto en manejos de morocotos. Se concluye que el eugenol es un anestésico adecuado para morocotos juveniles con peso de 256.6 ± 73, 18 g, pudiendo ser utilizado en concentraciones de 50 mg. L-1 de eugenol...