Nutrition Through the Life Cycle Nutrition of Ornamental Fish: Water Soluble Vitamin Leaching and Growth of Paracheirodon innés/1

Ornamental fish keeping has become an increasingly popular hobby, and there are now more than 330 mil lion ornamental fish sold each year throughout the world (Riehl and Baensch 1989). Although the total number of fish species exceeds 30,000 (Friede 1987), only 4000 of these species classify as freshwater or namental species (Riehl and Baensch 1989). Of these species a few hundred are popular and are generally available to the hobbyist. In contrast to the popularity and the scale of the ornamental fish hobby the knowl edge of the nutritional requirements of popular or namental fish species kept in captivity has received very little attention. The present knowledge of the nutritional requirements of fish are limited to a small number of species that are important in the aquacul ture food-fish industry (NRC 1981, 1983). Except for goldfish (Carassius auratus) and a small number of tropical freshwater carnivorous fish species (i.e., some Cichlidae spp), ornamental fish are rarely kept in a single species environment. In a multi species tank, representatives of herbivore, omnivore and car nivore fish species share a common environment in which they feed on a single diet. Nutritional strategies for ornamental fish highlight the need to strike an equilibrium in the dietary formulation between the requirements of herbivorous and carnivorous species when delivering diets for community fish species. More critical than the dry matter formulation is the distribution of food between individuals of one species and between different species kept in the same aquar ium. The physical characteristics of the diet also plays an important role when species of various weights, from 0.15 g (Characidae) to >20 g (Cichlidae), aie fed on one diet. Diets need to be small enough for the smaller species but large enough to be identified and eaten by the larger species. Natural hierarchy between individuals within one specie and across species (Milinski 1993) is further exacerbated during feeding be cause not all ornamental species will consume food from the surface or the bottom of the tank. In their native habitat most species will forage for food during the day and are not adapted to rely on a single meal; they do not have a defined stomach and are therefore unable to temporarily store large quantities of food. The smallest species of ornamental fish (Characidae) have a high metabolic rate and require a frequent sup ply of food to sustain growth or maintenance. Materials and methods. Study 1. The effect of feed frequency on growth of neon tetras (Parachei rodon innesi) was carried out using 120 fish, with an average bodyweight of 0.1705 ±0.004 g, which were purchased from a local dealer and quarantined for a period of 4 wk before the trial. The fish were fed ex perimental diet 1, which was a steam drum-dried, flaked product with 39.0% protein, 12.7% fat, 30.0% carbohydrate, 13.3% ash, 4.8% moisture and GE 19.66 MJ • kg~' and a particle size of 2 mm. Fifteen randomly