Comparison of Cultivated Tubifex Worm (Tubifex tubifex) Powder and Commercial Tubifex Worm on Growth Performance and Immunity Indices in Angel Fish (pterophylum scalare) Resistance to Air exposure Challenge Stress

The aquaculture industry in the world, with an 8-million-dollar transaction rate, has 8% growth annually. It also has the most value-added rate among different fishery activities based on the food and Agriculture Organization (FAO). The angelfish belonging to Cichlid family, is known as a famous species in this industry. This fish feeds on various live feedstuffs. Regarding the significance of suitable feedstuffs in aqua feed industry, the live feeds used to provide nutritional requirements, immunity tuning and stimulation will be of important. Tubifex worm, containing considerable crude protein, diverse sorts of amino acids and essential fatty acids, has a deserving role and checking the nutritional value of Tubifex worm with aim of improving the growth performance, boosting immune responses and survival rate, reducing expenditure cost and increasing productivity is so crucial. The objective of the current experiment was to compare the effect of the cultured and commercial Tubifex worm powder in the diet of juvenile angelfish on growth performance and immune responses. The experimental rations included 3 rations: 1) control ration as pellet 2) commercial Tubifex powder as freeze-dried food and 3) the rations containing mass-produced Tubifex as freezedried food. One-hundred thirty five Angel fishes with an average initial weight of 0.2± 0.5 gr were tested for 63 days. The fishes were placed randomly into nine 920 liter-capacity of 15 fishes. The average temperature was (27±1˚C), pH (7.5±0.1) and dissolved oxygen (7.68±0.35) was regulated according to required conditions. The length of light-dark cycles was considered 14 and10 hours, respectively.The fishes were fed 3% body weight in three times a day (7, 13 and 20). Biometry was conducted at 1st, 31st and 63rd days and the criteria related to the growth performance, nutrient utilization efficiency and survival rate were computed. At the end of the experimental period, five samples were taken from each aquarium, exposed to the airchallenge for 3 min and bleed 3 h after challenge. After that, biochemical analyses including trypsin, amylase and lipase were measured by using benzoyl-arginine p-nitroanilide substrate, starch and olive oil as substrate, respectively through titration method. At the end of the experimental period, total immunoglobulin, lysosome and complement, liver enzymes including ALT and AST were measured by kinetic enzymatic method and the microbial parameters including (plate count agar, and lactobacilus conut were measured. Chemical analysis of experimental diets including crude protein by Kjeldahl method, crude fat by Soxhelt extractor and ash by electrical furnace were measured. Normality Test of was done by Shapior-wilk test. Analysis of alterations in growth performance, nutritional and biochemical factors were done by one-way analysis of variance (ANOVA) and comparing means based on Duncan multiple test using SPSS software, version19.0. The highest rate of final weight (about 30%), initial length (about 14%) and the rate of special growth (about 27%) were belonged to the angel fishes fed on the diet containing cultured Tubifex. The activity of the immunity parameters including total immunoglobulin, lysosome as well as complement were also significantly higher in the treatment with the diets containing Tubifex after air exposure challenge. The activities of the lipase, protease and amylase increased in the culturing Tubifex treatment in compared with two other ones. The number of the intestinal lactobacillus indicated that the most colonies forming unit of lactobacillus was significantly higher in angel fish fed the diet containing cultured Tubifex treatment. The results indicated that the angel fishes fed on the cultured Tubifex showed higher weight increment, special growth rate, survival rate as well as better nutrient utilization efficiency which may be attributed to the existence of higher rate of protein, unsaturated fatty acids Improvement of the immunity in fish fed the diet containing cultured Tubifex can be related to the role of lysosome as an important factor in natural perseverance for fishes, immunoglobulin as an important factor in antibody secretion as well as complement which has a basic role in acquired natural immunity for the fishes. The enzymes ALT and ALP which have an important role in using amino acids in oxidation process The increase of intestinal LAB count in angel fish fed the cultured Tubifex can be enhanced absorbing nutrients, disease resistance and finally, higher growth performance Considering the higher mortality rate among the larvae in the first 20-30 days and the initial time of the active feeding because of changing the nutritional modes, use of Tubifex worm powder as a live food may be effective in better growth function, external form as well as promotion of immunity system for the fishes. Conclusion: Feeding the angel fishes on cultured Tubifex worm powder especially in the initial steps of the active feeding may result in improvement in growth performance and some specific and nonspecific immune responses.