Guppy

 In tetrapods, the functional (classical) class I and class II B loci of the major histocompatibility complex (Mhc) are tightly linked in a single chromosomal region. In an earlier study, we demonstrated that in the zebrafish, Danio rerio, order Cypriniformes, the two classes are present on different chromosomes. Here, we show that the situation is similar in the stickleback, Gasterosteus aculeatus, order Gasterosteiformes, the common guppy, Poecilia reticulata, order Cyprinodontiformes, and the cichlid fish Oreochromis niloticus, order Perciformes. These data, together with unpublished results from other laboratories suggest that in all Euteleostei, the classical class I and class II B loci are in separate linkage groups, and that in at least some of these taxa, the class II loci are in two different groups. Since Euteleostei are at least as numerous as tetrapods, in approximately one-half of jawed vertebrates, the class I and class II regions are not linked.

Deltamethrin, a synthetic pyrethroid pesticide contaminating aquatic ecosystems as a potential toxic pollutant, was investigated in the present study for acute toxicity. Guppy fish (Poecilia reticulata) were selected for the bioassay experiments. The 48-h LC50 was determined for the guppies. The experiments were repeated three times and a total of 210 guppies were used. The static test method of acute toxicity test was used. In addition, behavioral changes at each deltamethrin concentration were determined for the individuals. Data obtained from the deltamethrin acute toxicity tests were evaluated using the Probit Analysis Statistical Method. The 48-h LC50 value for guppy was estimated as 5.13 μg/L.

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.Les exigences alimentaires des poissons d'ornementation. Les exigences alimentaires des poissons d'ornementation. L'élevage de poissons ornementaux effectué pendant plus de trois siècles et le développement de la manufacture d'aliment depuis 50 ans ont contribué à l'essor de ce loisir, mais la nutrition des poissons ornementaux se fonde sur une extrapolation de données dérivées de poissons de consommation et en conditions de culture intensive. Quelques études ont été faites sur les besoins alimentaires (en protéines, en éléments minéraux) d'espèces ornementales d'eau douce (des poissons vivipares) dans le cadre de production, à Singapour en particulier, et sur la nécessité d'aliment vivant dans les premiers stades de leur cycle de vie. Les besoins protéiniques varient de 30 % de protéine brute pour le poisson rouge omnivore (Carassius auratus), jusqu'à 50 % pour le discus carnivore (Symphysodon aequifasciata). Les besoins en minéraux (phosphore, fer, magnésium et zinc) ont été étudiés pour le guppy (Poecilia reticulata), mais peu d'investigations ont été faites pour connaître les besoins vitaminiques des espèces ornementales. Les besoins en acides gras ont été étudiés chez les poissons ornementaux marins (demoiselles, hippocampes) et se limitent à la supplémentation diététique en acides gras très insaturés n-3. Que les poissons soient présentés en aquariums publics ou cultivés en aquariums personnels, un problème de diversité d'espèces se pose dans un même bassin ; chaque espèce ayant ses exigences spécifiques. Leur besoin énergétique d'entretien varie de 0,07 kJ/jour pour les petits néons-tétras (Paracheirodon innesi) jusqu'à 0,51 kJ/jour pour les gouramis serpents (Trichogaster microlepsis), élevés dans une eau à 26 °C. Dans la recherche sur les besoins alimentaires des poissons ornementaux, il faut utiliser des paramètres adéquats, autres que le taux de croissance pour obtenir les taux optimaux des nutriments.