Globally, Siamese fighting fish (Betta splendens) continue to be sold and kept in small, barren jars or tanks, with little concern for their welfare. This study aimed to examine the impact of housing size and furnishings (i.e. live plants, refuges) on the behaviour of Siamese fighting fish, to understand optimal tank conditions. Thirteen male Siamese fighting fish were rotated between five different housing conditions: ‘jar’ (1.5 L); ‘small’ (3.3 L); ‘medium’ (5.6 L); ‘large’ (19.3 L); and ‘large-barren’ (19.3 L). All tanks had gravel and furnishings, except the large-barren tank which was devoid of these. Overall, tank size influenced behaviour. Fish were significantly more active and spent significantly less time resting and performing ‘abnormal’ behaviours (hovering and stereotypic swimming), in the large tank compared to the smaller tanks. Tank furnishings also influenced behaviour. Fishes in the large-barren tank performed more ‘abnormal’ behaviours (hovering, stereotypic swimming, interaction with the walls), compared to the large tank which had furnishings. These results suggest that the small, barren jars and tanks that Siamese fighting fish are often housed in are detrimental to their welfare, and larger, furnished tanks are more optimal. Behavioural variations were observed between the fish in this study, highlighting individual fish personality. We recommend a minimum tank size of 5.6 L for the display and sale of Siamese fighting fish, and tanks larger than this for keeping Siamese fighting fish at home. All tanks should contain gravel, live plants and refuges.

This study aimed to analyze the influence of different temperatures on the embryonic and larval development of discus fish Symphysodon aequifasciatus and determine the time required for the beginning of exogenous feeding. Eggs and larvae were obtained from natural spawns and distributed in five treatments: 24.0, 26.0, 28.0, 30.0, and 32.0 °C. To assess the developmental stages and embryonic structures, samples were taken at regular intervals and checked under an optical microscope. At the end of the experimental period, statistical analysis was performed, followed by Tukey’s test. As a result, it was possible to observe the significant effects of temperature on the variables. It was noted that the temperature accelerated the embryonic and larval development of the discus and also contributed to a reduction in the time between the incubation period and the feeding transition. It was also noted that the incubation of eggs and larvae at a temperature of 24.0 °C can cause damage to embryos, such as malformation of the body as well as anomalies in the circulatory system.

Brazilian basslet Gramma brasiliensis is a fish highly appreciated by the marine ornamental industry. There is an increasing interest in the development of a breeding protocol for this species. However, descriptions of the reproductive biology, eggs and larval development are scarce. This study was the first to describe the spawning, eggs and larvae of G. brasiliensis in captivity, including mouth size information. Six spawning events produced egg masses with 27, 127, 600, 750, 850, and 950 eggs. Larger egg masses showed embryos with at least two different developmental stages. Eggs are spherical (∼1.0 mm diameter), held together by filaments entangling chorionic projections. Larvae with fewer than 12 hph (hours post-hatch) presented 3.55 mm standard-length, well developed eyes, fully absorbed yolk sac, an inflated swim bladder and mouth opened. Exogenous feeding on rotifers began within 12 hph. The average mouth width at first feeding was 0.38 mm. The first settled larva was noted by day 21. This information should help to determine appropriate diets and prey-shift time during the larviculture of the species.

The flameback pygmy angelfish Centropyge aurantonotus, highly appreciated and valued by the aquarium market, is heavily harvested and traded. Temperature is one of the abiotic factors that has the most influence on fish development, especially in the early stages of life. For captive production, it is essential to know the appropriate environmental parameters for each species. In this sense, this study aimed to evaluate the influence of temperature on the embryonic development and hatching rates of C. aurantonotus incubated at six different temperatures (20, 22, 24, 26, 28, 30°C). Embryonic development events were very similar in terms of morphological and chronological characteristics compared with other species of the genus Centropyge. Incubation time was inversely proportional to temperature. The treatment at 22°C required twice the time of that required by 30°C treatment for hatching to occur. The best incubation temperature range was 24–28°C. Values below 22°C and at 30°C showed lower hatching rates compared with other treatments. Based on these results, the recommended temperature at which to incubate C. aurantonotus eggs is between 24–28°C.

Temperature is an environmental factor that influences the development of fish, and when changed abruptly can lead to high mortality. Some species of fish are influenced by this factor, exhibiting a longer time for embryonic development and time to first feeding. This study aims to evaluate the effect of water temperature on embryonic and larval development up to first feeding, to describe the time in hours post fertilization (hpf) of the emergence of different structures and to determine the best hatching rate and survival of animals under different treatments. Five different egg incubation temperatures were used (24, 26, 28, 30 or 32°C, respectively). The eggs were observed at regular intervals of 30 min up to 24 h, every 2 h until 48 h and every 4 h until the display of first feeding in all treatments. Embryonic development was longer for eggs incubated at 24°C and the best results for hatching rate and survival of spawning efficiency were at 28°C. We recommend that incubation of Trichogaster leeri eggs is carried out at 28°C up to the first feeding of larvae.

The present study aimed to provide data on the time required for Melanotaenia boesemani to complete embryonic development, and to investigate the influence that incubation at different temperatures caused in this species. The effects of temperature on the time and hatching rate are presented, as well as information related to embryonic development stages. After fertilization, the eggs were kept in incubators at 23, 26, 29 or 32°C and observed at predetermined times until the moment of hatching. Stages of development were identified and classified according to morphological and physiological characteristics. Oil droplets were visualized inside the eggs as well as filament adhesion present at the chorion. Embryonic development was similar to that observed in other species of the genus Melanotaenia with hatching and faster development in higher temperatures.

Dwarf rainbowfish (Melanotaenia praecox) are an ornamental fish with a high added value and considerable commercial interest. However, little information is known about the organism's reproductive biology, especially the early stages of embryonic development (initial ontogeny). Melanotaenia praecox embryos were examined throughout development to describe the dwarf rainbowfish initial ontogeny. Eggs were incubated at 28°C, and observations were recorded at pre-determined times. Development stages were identified and classified according to morphophysiological characteristics. The initial size of the eggs ranged between 0.99 and 1.04 mm. Oil droplets were observed in the eggs, and fixing filaments for adhesion were observed in the corium. Embryonic development was similar to that of other species in the genus Melanotaenia, in which hatching begins 119.50 h post-fertilisation or 3405.75 degree-h post-fertilisation. The main features of the newly hatched larvae were excellent swimming activity, a reduced yolk sac, mouth movement and an apparently functional digestive system.

Hatchlings of clown loach (3.8 mm in total length, TL) are pelagic. Whenreared at 26−28 °C, they become benthic 3 days after hatching (dah), when their swimbladder is inflated. The fin development sequence (pectorals  <  caudal  < dorsal  =  anal  <  pelvic) is typical of the clade Ostariophysi. All fins andfinrays are fully elongated at 20 mm TL, but the finfold persists until25 − 26 mm TL (start of juvenile stage). Melanophores appear at 3 dah,they form a 5-bar pattern at 5 dah, then two bars (III and V) vanish progressively,producing at 26 mm TL the 3-bar pattern that is typical of adults.Throughout the ontogeny, the pigment pattern exhibits a structural regularity (bars spacedat regular intervals), which is interpreted in a functional perspective by reference tothe maintaining of crypsis and signalling throughout. Exogenous feeding commences at 4 dah(5.5 mm TL). Food intake (FI) increases rapidly, from 6%wet body mass (WM) at 5.5 mm TL to  >20%WM in fish  > 7 mm TL. Gut evacuation rate(Rg) increases with increasing meal sizeand fish size, as a result of gut coiling (from 8 to 15 mm TL), and ishighest at 11 mm TL (about 10% WM h-1 in fishfeeding maximally). The allometric increase of FI andRg during the early larval stages isaccompanied by increasing capacities for growth, so early sizes differences amplifyrapidly during the ontogeny. Nevertheless, growth remains slow (mean of 0.4 mm TLday-1 from 4 to 29 dah; 0.9 mm TL day-1for top growers). By contrast, unfed fish display long resistance to starvation (until14−15 dah). The combination of slow growth and long resistance to starvation is discussedin respect to the reproductive phenology of the species, as the capacity of makingmetabolic economies prevails over fast growth for seasonal strategists spawning mainly atthe start of the rainy season.

The knowledge of how fish survive and grow at different temperatures, and how these traits vary between life stages, is essential to evaluate the effects of climate change on wild fish and implement effective strategies in aquaculture. These issues are addressed in this study through a series of experiments that evaluate the effect of temperature (23–34 °C) on the embryos and larvae of clown loach, Chromobotia macracanthus. This species is endemic to the rivers of Sumatra and Borneo, highly praised on the ornamental fish market, and has been reproduced in captivity recently. No embryo survived a 24-h exposure to 34 °C until the age of 3 days after hatching (dah); mortality was high at 32 °C at 2 and 3 dah, whereas it was low and similar from 1 to 4 dah at 23–29 °C (<10%). Yolk absorption was proportional to water temperature (Q10°C of 1.69 in the 23–32 °C range), but fish reared at cold temperatures were larger than others at the start of exogenous feeding (5.7 vs. 5.5 mm TL, at 23 and 32 °C, respectively). The survival of larvae fed Artemia nauplii ad libitum was high at 23–32 °C (80–100%), but almost null at 34 °C. Growth models at different temperatures were produced from weekly measurements in two experiments, and tested by comparing their predictions with the results of a third experiment. Throughout the larval stage, the optimal temperature for growth (T°opt) was close to 29 °C, and departures from T°opt resulted in substantial growth penalties (–30% SGR for –5.1 °C and  + 3.1 °C). High survival, fast growth (0.7 mm day-1) and limited size dispersal at T°opt are encouraging perspectives for the aquaculture of clown loach. From an ecological perspective, the species has an atypical thermal biology, as it is less thermophilic than other tropical fishes, but more stenothermal than temperate fishes exhibiting similar values of T°opt, both traits being of particular concern in the context of global warming.

The clown loach Chromobotia macracanthus, endemic to Indonesia, is amajor species on the international market of ornamental freshwater fish. In order tosatisfy an increasing demand with a sustainable alternative to the massive capture of wildjuveniles, research has been dedicated to the artificial propagation and domestication ofthis species. The present study, the first of a series, focused on favourable maintenanceconditions for broodfish sexual maturation, criteria for identification of ripe fish,efficiency of hormone-induced breeding treatments, predictability of their latencyresponse, and on the comparison of reproductive performances of fish from populations ofSumatra and Borneo Islands (in total, 112 females of 46 to 404 g body weight). When rearedin fully controlled conditions in large water recirculation systems, broodfish originatingfrom Sumatra had reproductive performances similar to or slightly higher than thosematuring in the wild (ovulation rate of 93% vs. 82%, relative fecundity of 109 277 vs.103 550 ova  kg-1 and fertilization rate of 73% vs. 61%, respectively). In thesame rearing conditions, captive females from Borneo (n = 22) showedlower ovulation rate (77%), relative fecundity (76 262 ova kg-1) andfertilization rate (50%) than those originating from Sumatra (n = 28). Bycontrast, the mean individual weight of ova (around 0.8 mg) was independent from theorigin or maintenance conditions of females. An initial modal follicle diameter  ≥1.02 mmgenerally led to high ovulation success (>80%) after hormonal treatment and isrecommended as the main criterion for selecting female broodfish. Two hormonal treatmentsfor inducing oocyte maturation and ovulation (T1: two successive injections of Ovaprim ata 6 h-interval; T2: one injection of human chorionic gonadotropin (hCG)- and one ofOvaprim 24 h later), produced similar results in terms of ovulation rate, quantity andquality of ova collected. With both treatments, the latency decreased with increasingwater temperature, then increased again at temperatures  >28–29 °C. To ourknowledge, such U-shaped relationship between the latency response andtemperature has never been documented in teleost fishes.

Clinical haematology and blood plasma chemistry can be used as a valuable tool to provide substantial diagnostic information for fish. A wide range of parameters can be used to assess nutritional status, digestive function, disease identification, routine metabolic levels, general physiological status and even the assessment and management of wild fish populations. However to evaluate such data accurately, baseline reference intervals for each measurable parameter must be established for the species of fish in question. Baseline data for ornamental fish species are limited, as research is more commonly conducted using commercially cultured fish. Blood samples were collected from sixteen red top ice blue cichlids (Metriaclima greshakei), an ornamental freshwater fish, to describe a range of haematology and plasma chemistry parameters. Since this cichlid is fairly large in comparison with most tropical ornamental fish, two independent blood samples were taken to assess a large range of parameters. No significant differences were noted between sample periods for any parameter. Values obtained for a large number of parameters were similar to those established for other closely related fish species such as tilapia (Oreochromis spp.). In addition to reporting the first set of blood values for M. Greshakei, to our knowledge, this study highlights the possibility of using previously established data for cultured cichlid species in studies with ornamental cichlid fish.

Aqua feeds should be formulated to provide complete and balanced nutrition to achieve optimal health and growth in fish, including adequate levels of essential amino acids (EAA). There are few or no data relating to the EAA requirements for ornamental fish species, with the majority of quantitative data for these nutrients being available for commercially farmed fish. The determination of EAA requirements is usually established through dose–response studies, which can be costly and time consuming, especially if determining the requirement for many amino acids (AA). An alternative method for predicting the EAA of fish, which is also relatively fast and inexpensive, is the assessment of whole-body AA composition. A total of eight goldfish with a mean wet weight of 34·2 (sem 1·4) g were obtained as a result of a routine cull by breeders. The fish were freeze-dried and AA was content analysed by hydrolysis or performic ‘acid’ oxidation. EAA values ranged between 0·97 (sem 0·02) for tryptophan and 7·9 (sem 0·14) for lysine (g/100 g AA). Compositional data were also used to estimate the essential amino acid ratios of these fish. The findings are in agreement with those for juvenile common goldfish, suggesting that there are no differences in whole-body AA composition between juvenile and adult, or fancy and common goldfish. However, these indices do not provide a quantitative total amount of each AA required by the fish, but can be used proportionally to provide guidelines to formulate diets for ornamental species.

Silver arawana Osteoglossum bicirrhosum are increasingly popular on the international aquarium fish market, but the routine killing of mouth brooding adults to collect juveniles for the trade may threaten wild populations. We describe the aquarium trade and fishery for silver arawana in the Peruvian Amazon. This is the first such report on the species for South America, and is based on field interviews with trade participants and fishermen, and on a review of government statistics. The regional trade is large, expanding and valuable (over 1 million juveniles worth USD 560,000 exported in 2001), of considerable economic importance to the rural poor, and in urgent need of research, monitoring and management. Outright bans on arawana fishing are likely to be ineffective and to destabilize an export fishery that provides significant part-time employment for the rural poor and substantial foreign earnings. Experimental studies are called for that compare the impacts on arawana yields of alternate fishing techniques, such as catch and release of brooding males, as a basis for developing more effective management schemes in Amazonia.

Although fish have been kept for more than three centuries as ornamentals, and the development of manufactured feed since 50 years ago has contributed to the tremendous growth of this hobby, nutrition of ornamental fish is based on extrapolation of results derived from food fishes under intensive farming conditions. Some research on nutrient (protein, minerals) requirements of growing freshwater ornamental species (live-bearers) in a production environment has been conducted, mainly in Singapore, with emphasis on the provision of live feed during the early stages of the life cycle. Protein requirements varied from around 30% dietary protein for growing omnivorous goldfish (Carassius auratus) to 50% for the carnivorous discus (Symphysodon aequifasciata). Whereas mineral (phosphorus, iron, magnesium, zinc) requirements have received some attention in the guppy (Poecilia reticulata), few researches have concentrated on vitamin requirements of ornamental species. Requirements for fatty acids have been conducted mainly on marine ornamentals (damselfish, seahorses), and accentuated the need for dietary supplementation of n-3 highly unsaturated fatty acids. Fish kept in public and home aquaria presents the problem of diversity of species in the same enclosure, each with its own specific requirements and needs. Maintenance energy levels of ornamental fish varied from 0.068 kJ per day for small neon tetras (Paracheirodon innesi) to 0.51 kJ per day for moonlight gouramis (Trichogaster microlepsis) kept at a water temperature of 26 °C. Research on nutrient requirements of ornamental fish urges for suitable measurements other than only growth rate in order to determine optimal dietary inclusion levels.