Betta Research Articles

Uso do sal comum (NaCl) e densidade de estocagem durante a larvicultura de Betta splendens.

Este trabalho avaliou o desempenho produtivo e a sobrevivência de larvas de Betta splenden ssubmetidas a diferentes concentrações de sal comum (NaCl:0, 2, 4, 6 e 8 g L-1), e densidades de estocagem (1, 5, 10 e 15 larvas L-1). Para tanto foi utilizado delineamento inteiramente casualizado em esquema fatorial 5X4 com três repetições. Ao final do experimento foram avaliados o peso, comprimento, uniformidade, taxa de crescimento especí­­fico e sobrevivência. A salinização da água com 2 g L-1 permitiu maiores valores de comprimento total í­Â s larvas criadas nas densidades elevadas de 10 e 15 larvas L-1. Em relação aos demais parí­¢metros avaliados, não houve interações entre a adição de sal e a densidade de estocagem. Independentemente da adição de sal, o melhor desenvolvimento ocorreu em densidades de até 5 larvas L-1. Assim, recomenda-se densidade de estocagem de 5g L-1em água salinizada (2 g L-1) para a larvicultura de Betta splendens.

Ní­­veis de proteí­­na bruta em dietas para juvenis de beta

Com o presente estudo objetivou-se avaliar as exigências por proteí­­na bruta para juvenis de Betta splendens. Foram utilizadas dietas isocalóricas com seis ní­­veis de proteí­­na bruta (27, 31, 35, 39, 43 e 47%), em delineamento inteiramente casualizado, com quatro repetições. Peixes com peso médio de 0,11 ± 0,02g foram alimentados três vezes ao dia, por 30 dias. Ao final do experimento avaliou-se: taxa de sobrevivência (TS), ganho de peso (GP), consumo de ração (CR), consumo de proteí­­na (CP), conversão alimentar (CA), taxa de eficiência protéica (TEP) e taxa de crescimento especí­­fico (TCE). Para os parí­¢metros de desempenho produtivo CR, CA e TEP observou-se efeito linear negativo dos ní­­veis de proteí­­na bruta na dieta (p < 0,05). Observou-se efeito quadrático dos ní­­veis de proteí­­na da dieta para TS, GP e TCE, sendo 30,95%, 33,13% e 29,55% de PB os valores estimados para maximizar os respectivos parí­¢metros de desempenho produtivo. Dessa forma, conclui-se que a exigência por proteí­­na para juvenis de Betta splendens está entre 30 e 33% PB.

Effects of dietary mannan oligosaccharide on the growth, survival, intestinal morphometry and nonspecific immune response for Siamese fighting fish (Betta splendens Regan, 1910) larvae

A 28-day experiment was carried out to evaluate the effect of dietary prebiotic mannan oligosaccharide (MOS) on the growth, survival, intestinal morphometry and nonspecific immune response of the Siamese fighting fish ( Betta splendens Regan, 1910) larvae. The MOS supplementation levels evaluated was: 0, 2, 4 and 6 g kg -1 . Into 16 plastic aquaria (3 L) 240 larvae (4.21 ± 0.26 mm) were distributed at a density of 5 larvae L -1 . All larvae received live food for seven days, followed by a period of eight days of co-feeding (live food + inert diet) and, finally, 13 days of inert diet. At the end of feeding-trial, there were no significant differences between growth, survival, intestinal morphometry and alkaline phosphatase activity of larvae fed the control or MOS supplemented diets. However, the lysozyme activity in larvae fed 2 g MOS kg -1 was significantly higher compared to other treatments. For fish farming, the most beneficial effects of prebiotics reside in its ability to enhance the immune system of fish. In this context, this study revealed that, although the MOS supplementation has no effect on growth, survival and intestinal morphometry, 2 g MOS kg -1 supplementation for B. splendens larvae hint at a possible immunomodulatory effect, as evidenced by the increase in lysozyme activity

Male Siamese fighting fish use gill flaring as the first display towards territorial intruders

The Siamese fighting fish (Betta splendens) is well known as an aggressive fish with unique spawning and parental care behavior. During reproduction, male fish construct a bubble nest, court females, protect the brood, and defend the territory through aggressive displays. Aggression in male Siamese fighting fish has long been the subject of investigation; however, the kinematics of aggression during contests have been largely overlooked. Here we investigated how nest-holding, male Siamese fighting fish use two different types of displays, gill flaring and fin spreading, towards intruders during various reproductive phases; before (BB) and after bubble nest building, and after spawning (AS), and hatching (AH). Males were more aggressive towards male than female intruders and the level of aggression changed significantly between reproductive phases. Gill flaring, the more energetically costly display, was the dominant initial display towards male and female intruders in BB, AS, AH phases. However, defending males switched to fin spreading after prolonged exposure to intruders. The results suggest that Siamese fighting fish use gill flaring as an acute response in order to defend their territory; this response may be replaced by fin spreading as a chronic response, probably to reduce the energetic costs during the contest.

Individual boldness traits influenced by temperature in male Siamese fighting fish

Temperature has profound effects on physiology of ectothermic animals. However, the effects on temperature variation on behavioral traits are poorly studied in contrast to physiological endpoints. This may be important as even small differences in temperatures have large effects on physiological rates including overall metabolism, and behavior is known to be linked to metabolism at least in part. The primary aim of this study was to determine the effects of ambient temperature on boldness responses of a species of fish commonly used in behavioral experiments, the Siamese fighting fish (Betta splendens). At 26°C, subjects were first examined for baseline behaviors over three days, using three different (but complementary) ‘open field’ type assays tested in a fixed order. Those same fish were next exposed to either the same temperature (26°C) or a higher temperature (30°C) for 10days, and then the same behavioral assays were repeated. Those individuals exposed to increased temperatures reduced their latency to leave the release area (area I), spent more time in area III (farthest from release area), and were more active overall; together we infer these behaviors to reflect an increase in general ‘boldness’ with increased temperature. Our results add to a limited number of studies of temperature effects on behavioral tendencies in ectotherms that are evident even after some considerable acclimation. From a methodological perspective, our results indicate careful temperature control is needed when studying behavior in this and other species of fish.

Development of the digestive tract in first feeding larvae ofBetta splendensRegan, 1910

The aim of this study was to analyse the development of the digestive tract of Siamese fighting fish larvae (Betta splendens Regan, 1910), from hatching to 92 hours post-hatching (hph) at 28.0°C, in order to determine the most appropriate time to begin exogenous feeding (live feed) and to investigate the digestive tract and its function during larval development. At hatching (29 hours post-fertilization), the digestive tract was a simple and straight undifferentiated tube lined by a single layer of columnar epithelial cells; the mouth and anus were closed. At 18 hph, the mouth was open. At 32 hph, the tongue was located in the depression of the buccopharyngeal cavity floor and supported by basal cartilage. Goblet cells were present in the epithelium lining the pharynx and oesophagus. At 56 hph, the midgut had four distinct layers: the mucosa with typical villi, the submucosa, the smooth muscle layer, and the serosa. Histological analysis revealed that the larvae retained endogenous yolk reserves until 74 hph. Lipid accumulation was observed in the liver, which coincided with complete yolk absorption. At this time, the digestive tract was fully open and functional. Thus, it can be concluded that live feed should be given to B. splendens larvae from 74 hph onward, when the larvae are able to consume the food provided. This study also provides useful data for the improvement of husbandry techniques and for the formulation of diets specific to ornamental fish larvae.

Anaesthetic efficacy of clove oil-coated LDPE bag on improving water quality and survival in the Siamese fighting fish, Betta splendens, during transportation

With brilliant colouration and long, flowing fins, the Siamese fighting fish (Betta splendens) is one of the most popular species of freshwater aquarium fish. In the ornamental Siamese fighting fish business, stress is one of the major causes of fish injury, including collapse of the fins. To overcome this problem, attempts are being made to develop anaesthetic packaging, in which anaesthetic agents are coated onto low-density polyethylene (LDPE) packaging bags and released from the bags. The feasibility of using clove oil-incorporated methylcellulose-coated LDPE bag as a packaging material to induce an anaesthetic effect on Siamese fighting fish during transportation was also investigated. Based on a criterion of fish transportation within 2 days, concentrations of clove oil in anaesthetic-coated LDPE bag ranging from 0 to 11.67 mg L−1 were determined using an aqueous dilution method. Clove oil-incorporated methylcellulose-coated LDPE bags, filled with either 150 or 75 mL water and with equivalent anaesthetic concentrations, induced an anaesthetic effect in a similar manner. After 48 h of fish exposure, the water quality in clove oil-incorporated methylcellulose-coated LDPE bags was better than that of the control treatment. This study demonstrated that clove oil-incorporated methylcellulose-coated LDPE packaging bag could be successfully employed for transportation of Siamese fighting fish; in turn, this will minimize a dropped price when reaching the destination.

To breathe or fight? Siamese fighting fish differ when facing a real opponent or mirror image

Displays are a feature of animal contest behaviour and have been interpreted as a means of gathering information on opponent fighting ability, as well as signalling aggressive motivation. In fish, contest displays often include frontal and lateral elements, which in the latter involves contestants showing their flanks to an opponent. Previous work in a range of fish species has demonstrated population-level lateralization of these displays, preferentially showing one side to their opponent. Mirrors are commonly used in place of a real opponent to study aggression in fish, yet they may disrupt the normal pattern of display behaviour. Here, using Siamese fighting fish, Betta splendens, we compare the aggressive behaviour of males to a mirror image and real opponent behind a transparent barrier. As this species is a facultative air-breather, we also quantify surface breathing, providing insights into underlying fight motivation. Consistent with previous work, we found evidence of population-level lateralization, with a bias to present the left side and use the left eye when facing a real opponent. Contrary to expectations, there were no differences in the aggressive displays to a mirror and real opponent, with positive correlations between the behaviour in the two scenarios. However, there were important differences in surface breathing, which was more frequent and of longer duration in the mirror treatment. The reasons for these differences are discussed in relation to the repertoire of contest behaviour and motivation when facing a real opponent.

Expansion of the Known Host Range of the Microsporidium, Pseudoloma neurophilia.

The microsporidium, Pseudoloma neurophilia, is the most common infectious organism found in laboratory zebrafish colonies. Many currently used zebrafish lines originally came from pet store fish, and the initial description of P. neurophilia came from zebrafish obtained from a retail pet store. However, as P. neurophilia has not been described from wild-caught zebrafish, whether P. neurophilia is a natural pathogen of zebrafish is an open question. The pooling of fish of different species in the aquarium fish trade is common and a generalist parasite could be transmitted to novel hosts in this scenario. We determined that P. neurophilia can infect seven species of fishes from five families by cohabitation with infected zebrafish: Betta splendens, Xiphophorus maculatus, Devario aequipinnatus, Pimephales promelas, Oryzias latipes, Carassius auratus and Paracheirodon innesi. Infections in these fishes were histologically similar to those of zebrafish. We include a case report of a laboratory population of fathead minnows with naturally acquired P. neurophilia infections. With such a broad host range, including several fish families, other laboratory fishes should be screened routinely for this and other microsporidian parasites.

Acute toxicity and anaesthetic effect of clove oil and eugenol on Siamese fighting fish, Betta splendens

With brilliant colouration and long, flowing fins, the Siamese fighting fish (Betta splendens) is one of the most popular species of freshwater aquarium fish. In the ornamental Siamese fighting fish business, stress is one of the major causes of fish injury, including collapse of the fins. This problem could be solved by using anaesthetic treatment. Clove oil and eugenol were investigated for acute toxicity, which was determined using an aqueous dilution method at concentrations ranging from 0 to 35 mg L−1. Based on a criterion of fish transportation within 2 days, induction times of anaesthesia, fish behavioural responses and mortality, and recovery times were monitored and recorded over a 48-h period. The 48-h LC50 of clove oil and eugenol was 30.63 [with a 95 % confidence interval (CI) of 29.23–32.10 mg L−1] and 29.95 mg L−1 (with a 95 % CI of 28.50–31.48 mg L−1), respectively. Concentrations of 10 and 15 mg L−1 clove oil over a 48-h period induced a sedative effect, resulting in partial loss of reactivity and mobility while maintaining equilibrium. At these concentrations, the fish could recover behaviourally within 3–5 min. Recovery times decreased with lower doses and shorter exposure times. The higher the concentration of either clove oil or eugenol used, the lower the concentrations of total ammonia and un-ionized ammonia that were detected. This study revealed that clove oil and eugenol are highly effective anaesthetic agents as a transportation mixture for Siamese fighting fish.

Restrição alimentar no desempenho de machos do peixe beta (Betta splendens)

The aim of this study was to evaluate the effects of alimentary restriction on Betta splendens performance. For the experiment, 24 males were used, with initial average weight of 0.55 ±0.06 grams, distributed in 24 experimental aquaria with 1.5 liters of water without aeration in a completely randomized design, with four treatments and six repetitions. The treatments were: T1 – daily fed animals (control), T2 - fed for six days and one day of restriction (6A/1R), T3 - fed for five days and two days of restriction (5A/2R) and T4 - fed for four days with three days of restriction (4A/3R). The fishes were fed twice a day at 08:00am and 4:00pm. The variables studied were: final weight (FW), weight gain (WG), alimentary conversion (FC), average feed consumption (CMR), total length (CTOTAL), standard length (CPADRÃO) profile index (IPERFIL), condition factor (CF) and height. The results were submitted to variance analysis (ANOVA), and the means were compared by Tukey´s test at 5% of probability. No significant differences were observed for the following variables: water quality, survival, alimentary conversion and profile index. The best growth performance was observed when the feeding management of 6A/1R was applied.

Feed of Siamese fighting fish, Betta splendens, (Regan, 1910) in open pond: live and formulated diets.

The growth rate and percent survival of Betta splendens when submitted to formulated diet and live food treatments are evaluated. The three different diets were used and designated as: formulated diet (basal diet); live food diet (plankton) and mixed diet (formulated diet with plankton). The live food diet contained plankton belonging to an open pond. High mortality was reported with live food (plankton) treatment whereas higher percent survival occurred with formulated diet. Highest specific growth rate, weight gain and final weight were reported in the mixed diet treatment and were significantly different (p<0.01) from those in formulated diet and live food treatments. The gut contents of B. splendens in mixed diet and live food treatments comprised, Rotifera and Bacillariophyceae species in high percentages or rather, over 78% of total organisms. Lecane sp. was the most ingested zooplankton species by B. splendens in both treatments (mixed diet and live food), with the phytoplankton species Asterionella sp. and Melosira sp. respectively in mixed diet and in live food, respectively. Results indicated that the formulated diet influenced the water parameters dissolved oxygen, total suspended solids, total dissolved solids and pH. The live food in the open pond was not enough to improve the growth rate and percent survival of B. splendens. The growth performance of B. splendens; had the best results with mixed diet which was capable of maintaining species's survival (82%) and development in artificial conditions, benefiting the culture management of ornamental fish.

Prozac makes Siamese fighting fish timid

![Graphic][1] Hailed as a wonder drug since the mid-1980s, fluoxetine – the drug in Prozac – is on the World Health Organisation List of Essential Medicines. Used to treat human psychiatric disorders such as depression and post-traumatic stress disorder, fluoxetine is believed to increase

The toxicological effect of Ruta graveolens extract in Siamese fighting fish: a behavioral and histopathological approach.

The effects of pharmacological waste on aquatic ecosystems are increasingly highlighted in ecotoxicology research. Many of these products are designed for human physiology but owing to the conservative nature of vertebrate evolution they also tend to have effects on aquatic organisms and fishes in particular when they find their way into aquatic systems via wastewater effluent. One area of research has focused on reproductive control and the associated hormone treatments. Many of these hormones affect the reproductive physiology of fishes and may cause feminization of male reproductive traits. Alternative medicines have also been widely used particularly in traditional cultures but few of these alternative treatments have been assessed with respect to their potential impact on aquatic ecosystems. Rue (Ruta graveolens) has been used as a male contraceptive in traditional medicines but its effects on fish behavior and reproductive anatomy have yet to be established. Here we show that treating Siamese fighting fish, Betta splendens, with extract of rue has a significant effect on key aggressive/reproductive behaviors and the propensity to explore novel objects (boldness). In all cases the respective behaviors were reduced relative to controls and sham injected fish. Histological analysis of the testes revealed that rue exposure reduced the number of spermatozoa but increased the number of spermatocytes relative to controls.

GROWTH AND COLOUR PERFORMANCE OF THE CROSSBREED MARBLE STRAIN Betta splendens AND Betta imbellis

Betta ornamental fish of marble strain is a strain which is prefered by the hobbyists, because of its unique color, expensive price, and difficult to obtain the fish color strains. Therefore strain marble betta fish is still dominant for export quality for national and international contests. The aim of this study was to observe the growth and color performance of the crossedbreed marble strains of wild betta, Betta imbellis crossed with Betta splendens. The hybrids of B. imbellis (f) x B. splendens (m) (D) had a specific length and weight rate, (1,113 ± 0.04%/day; 2,531 ± 0.14%/day; 26.61 ± 2.02 mm) which was better than that of the hybrids B. imbellis (m) x B. splendens (f) (C) (1,099 ± 0.02%/day; 2,244 ± 0.13%/day; 25.97 ± 1.33 mm; and 0.0027 ± 0.0003 mm). However, the survival rate of the C hybrids (42.19 ± 11.42%) was higher than those of D (33.67%-17.08%). Based on the obtained results of the color identification the hybrids had as many as 15 characters of color, homozygous strains of marble which became the target of as much as 1%.

Complete mitochondrial genome of the Siamese fighting fish (Betta splendens)

The Siamese fighting fish (Betta splendens) is one of the popular aquarium fish. Serious attentions have been paid to the biodiversity of the fish. The mitochondrial genome of the Siamese fighting fish is reported to be 17 099 bp and includes 37 genes. The gene organization is similar to other fish mitogenomes. The control region is AT-rich and includes three tandem repeats. Phylogenetic analysis reveals that the fish is close to fish in the Macropodus genus. This mitogenome will assist in studying the mitochondrial variations and population structure in this fish and examine the evolutionary relationship among fish in the Osphronemidae family.

How Betta splendens finds its way

This study investigated the Siamese fighting fish Betta splendens performance in associating a stimulus with a specific cue when distractors are present. After trained to associate a specific color cue to a stimulus (conspecific) in a tank containing three colored distractors, the fish was challenged to locate the exact place where the stimulus fish was presented. With only color cues as guides, the Siamese fighting fish spent most of its time close to the color where the stimulus fish was previously presented, regardless of the distractors. However, fish trained to associate an empty place (no cues) to a stimulus fish, and then tested to localize the specific zone where the stimulus was shown, succeeded to locate the place even without any obvious cues/distractors for orientation. This study confirms that Siamese fighting fish show good conditioned learning and cannot be distracted by other stimuli. In addition, an unexpected good performance in the absence of cues may suggest the Betta’s ability to orientate by using another sensorial modalities, as magnetic orientation. Collectively, the results of this study confirm Betta as a valid and reliable model for learning and memory tests, and suggest more studies should be developed for the better understanding of the fish’s spatial orientation mechanisms.

UV-filter benzophenone-3 inhibits agonistic behavior in male Siamese fighting fish (Betta splendens).

Benzophenone-3 (BP-3) is a widely used organic UV-filter compound. Despite the frequent occurrence of BP-3 in aquatic environments, little is known about its effect on fish behavior. The aim of this study was to investigate the endocrine disrupting effects of BP-3 in male fighting fish (Betta splendens) with a focus on agonistic behavior. Male fighting fish were exposed to 10, 100, and 1000 μg/L BP-3, as well as a solvent control (0.1% ethanol) and a positive control (100 ng/L 17α-ethynylestradiol, EE2), for 28 days. At the beginning and the end of exposure, standard length and body mass of the fish were measured for calculating the condition factor (CF). In addition, spontaneous swimming activity (total distance moved) and agonistic behavior (maximum velocity and duration of opercular display in front of a mirror) were also quantified. At the end of exposure, the fish gonads were sampled for gonadosomatic index (GSI) measurement and histology. After the exposure, CF was significantly decreased in the 1000 μg/L BP-3 groups. Spontaneous swimming activity was not affected. However, maximum velocity was significantly reduced in the EE2 and 1000 μg/L BP-3 treatments; duration of opercular display was significantly decreased in the EE2 and 10 and 1000 μg/L BP-3 treatments. GSI was not significantly different between groups. There was a slight but statistically significant decrease of relative proportion of mature spermatozoa in testicular tissue in the 100 μg/L BP-3 treatment. Collectively, our results demonstrate that BP-3 can disrupt agonistic behavior of male fighting fish, indicating the endocrine disrupting activity of this compound.

Behavioral effects of fluoxetine on aggression and associative learning in Siamese fighting fish (Betta splendens)

Past research has implicated serotonin as an important neurotransmitter in the facilitation of aggressive behavior. In Siamese fighting fish (Betta splendens), the SSRI fluoxetine has been demonstrated to reduce both frequency and duration of aggressive displays across a variety of concentration exposure procedures. While this multi-method approach has provided strong evidence for fluoxetine's impact on aggression, no study has sought to examine the behavioral mechanism by which fluoxetine exerts its anti-aggressive effect. To address this question, a Go-No Go discrimination task utilizing mirror presentations as a reinforcer was designed. Consistent with previous reports, the results indicated that fluoxetine may exert a sedative effect upon aggressive behavior via decreased arousal to external stimuli.

Fluoxetine exposure impacts boldness in female Siamese fighting fish, Betta splendens

The present study examined the effects of the selective serotonin reuptake inhibitor, fluoxetine, on the behavior of female Siamese fighting fish, Betta splendens, in three different boldness assays (Empty Tank, Novel Environment, Social Tendency). When females were unexposed to fluoxetine, boldness was consistent within a context and correlated across assays. Fluoxetine exposure affected behavior within and among individuals on multiple levels. Exposure reduced overall boldness levels, made females behave in a less consistent manner, and significantly reduced correlations over time and across contexts. Fluoxetine exerted its effects on female Betta splendens behavior in a dose-dependent fashion and these effects persisted even after females were housed in clean water. If fluoxetine exposure impacts behaviors such as exploration that are necessary to an individual’s success, this may yield evolutionary consequences. In conclusion, the results show that fluoxetine exposure alters behavior beyond the level of overall response and highlights the importance of studying the behavioral effects of inadvertent pharmaceutical exposure in multiple contexts and with different dosing regimes.