Eugenol and tricaine methanesulfonate as anhestesics for the pearl cichlid

Anesthesia reduces the handling process duration and prevent fish injuries. The anesthetic effect and ideal concentrations of eugenol and tricaine methanesulfonate (MS-222) were tested for pearl cichlid (Geophagus brasiliensis) juveniles with an average weight of 4.4 g in water at 24ºC. The criterion for determining the optimal dose considered an induction time of one minute. Experiment 1 tested the concentrations of 25, 75, 150 and 300 mg L-1 of eugenol. The best results were obtained at doses of 150 and 300 mg L-1. Experiment 2 aimed to establish a more accurate result by testing the concentrations of 180, 210, 240 and 270 mg L-1, and led to an estimation of 217 mg L-1 of eugenol to induce anesthesia in one minute. Experiment 3 evaluated 200, 300, 400, 500 and 600 mg L-1 of tricaine, of which the concentration of 294 mg L-1 was estimated to induce anesthesia in one minute. No significant differences were observed for recovery times when using either of the anesthetics. No mortality was observed within 24 hours after the experiments for any concentration of the anesthetics. The present study recommends 217 mg L-1 of eugenol or 394 mg L-1 of tricaine for anesthesia of the pearl cichlid.

Influence of temperature on larval ontogenesis of Geophagus brasiliensis (Quoy & Gaimard, 1824) (Pisces: Cichlidae)

Summary Studies on the larval development of fish are essential for conservation and improvements in cultivation techniques. Geophagus brasiliensis popularly known as Cará has potential as a fish of interest in ornamental aquaculture. Wild adults of G. brasiliensis were kept in an aquarium for spontaneous reproduction. Newly hatched larvae were transferred to 5-litre aquaria at 22, 26 and 30°C until total yolk sac resorption. Histological slides were used for biometric analysis and monitoring of larval ontogenesis at different temperatures. Histologically, from the first to the fourth days it was possible to identify myomeres, optic vesicle, yolk syncytial layer, brain, heart and differentiation of the eye layers. From the fourth to the seventh days, it was possible to identify mandibular and gill cartilages, swim bladder, liver, prismatic epithelium with striated border in intestine and renal epithelium. All biometric measurements increased over the days, except height and length of the yolk sac, which gradually decreased until the complete resorption of the yolk sac that occurred on the fifth day at a temperature of 30°C, the sixth day at 26°C and the seventh day at 22°C. Morphological events at 30°C such as the reabsorption of the yolk sac, the appearance of cartilage in the branchial arches and differentiation of the layers of the eyes occurred faster compared with the other temperatures tested. Opening of the mouth and digestive tract occurred at a similar time on the fourth day in all temperatures.

HYDROCHEMICAL PARAMETERS AND BIOMETRIC DATA OF FISH SPECIES FROM THE BORORÉ, BILLINGS RESERVOIR, SÃO PAULO, BRAZIL

The artisanal fishing is an important activity in Billings Reservoir (São Paulo, Brazil) and there is a paucity of biometric data about the fish in this region. Thereby, it is important to provide data about ichthyofauna that can be used for future management actions. The aim of this study was to present some data about the water quality and biometric data on fish species collected at the Bororé site (Billings Reservoir). In general, the obtained hydrochemical data raised a concern about the water quality because some parameters were above the established limit for body water class 2. A total of 170 fish were captured, corresponding to seven species and one genus. Geophagus brasiliensis was the most representative species (36%), followed by Astyanax bimaculatus (25%) and A. eigenmanniorum (20%). The hepatosomatic index (HSI) data showed differences in energy displacement between the species; the highest HSI values were observed in Hoplias malabaricus (HSImale = 1.33 ± 0.20; HSIfemale = 1.17 ± 0.82) while the smallest HSI was observed in A. fasciatus (HSImale = 0.47 ± 0.14; HSIfemale = 0.68 ± 0.35).

GROWTH OF Geophagus brasiliensis REARED AT DIFFERENT TEMPERATURES AND FEEDING REGIMES

The aim of this study was to evaluate the growth performance of Geophagus brasiliensis rearedb under distinct temperatures (24.3 ± 0.9, 28.1 ± 1.0, and 31.7 ± 0.8°C) and feeding regimes (apparent satiety and a supply of 4% of the total biomass). About 500 wild-caught individuals were sorted and identified, to screen 180 fish to be used in the experiment (6.81 ± 1.15 g and 7.51 ± 0.47 cm). After a 55-day acclimatization period, the fish were distributed in experimental tanks, considering a double factorial randomized blocks scheme, composed of six treatments and three replicates. Growth performance parameters, somatic indexes and carcass yield were evaluated at the end of the experimental period (72 days). Fish fed to the point of apparent satiety presented higher (p <0.05) final weight, weight gain, specific growth rate and hepatosomatic index. The animals reared at a temperature of 24.3°C displayed higher (p <0.05) final weight, weight gain, specific growth, hepatosomatic index, lower visceral fat, and feed conversion index. It was concluded that G. brasiliensis presents higher productive indexes when fed until apparent satiety and reared in temperatures close to 24.3°C.

Caracterização seminal de carás (Geophagus brasiliensis - Cichlidae) induzidos artificialmente

Um estudo foi realizado com o objetivo de avaliar as características seminais do cará Geophagus brasiliensis mantido em cativeiro com e sem indução hormonal. Para tanto, foram utilizados 26 machos distribuídos entre os seguintes tratamentos: nove machos sem indução hormonal; nove machos com indução hormonal de extrato de hipófise de carpa (HC) e oito machos com indução hormonal por gonadotropina coriônica humana (HCG). Os parâmetros avaliados para a caracterização seminal nos diferentes tratamentos foram volume seminal, cor do sêmen, motilidade espermática, vigor espermático, tempo de latência, concentração espermática e viabilidade espermática. Os dados foram submetidos à análise de variância com 95% de confiança. A coloração do sêmen foi classificada como branco leitoso. Os valores médios para a motilidade, vigor espermático e concentrações dos espermatozoides foram: 94,44%, 78,75% e 63,88%; 4,44, 4,00 e 3,55; 5,10, 5,00 e 5,72 x 109 mL-1, para os tratamentos sem indução, HCG e HC, respectivamente. O tempo de latência espermático variou de 143,4 a 988,2 segundos e a viabilidade espermática foi de 100% para todos os tratamentos. A análise de variância não apresentou diferença significativa entre os efeitos dos diferentes tratamentos sobre nenhum dos parâmetros avaliados. Embora os resultados tenham demonstrado não ser necessária a indução artificial de machos durante o período reprodutivo, outros protocolos de reprodução artificial devem ser testados para G. brasiliensis vislumbrando o uso da espécie de forma comercial na aquicultura.