Plant Archives Volume 20 No. 2, 2020 pp. 6145-6150 e-ISSN:2581-6063 (online), ISSN:0972-5210 ANTIOXIDANT ACTIVITY AND HPLC ANALYSIS OF THE MARINE ALGAE HALYMENIA DILATA AS A POTENTIAL FISH FEED FOR POECILIA SPHENOPS Amthul Azeez 1 *, Beema Jainab 2 S.I. and Asma Fathima 1 1 *Department of Zoology, J.B.A.S. College for Women (Autonomous), Chennai (Tamil Nadu), India. 2 Department of Plant Biology and Plant Biotechnology, J.B.A.S College for Women, (Autonomous), Chennai (Tamil Nadu), India. Abstract Nowadays algal fishmeal is a principle source of protein in commercial aquatic feeds. Marine algae possess highly beneficial components that serve as a base and food for coastal fishes and aquatic organism. These marine algae are very important as they produce more oxygen. In the present investigation, the marine algae Halymenia dilata was collected from the coastal area and purified extract was prepared and optimized for the antioxidant activity and the presence of biologically active compound was analyzed by HPLC method. It was used as a potential fish feed for the ornamental fresh water fish Poecilia sphenops. The biochemical analysis and growth rate study further supported that the algae feed is better than the control feed. Key words: Marine algae, Halymenia dilata, antioxidant, HPLC and Poecilia sphenops Introduction Ornamental fishes must be reared in high density in indoor systems as they can’t scavenge freely on normal foods, and should be supplied with proper feeds. Complete diets should supply all the ingredients that are necessary for optimal growth and health of the fish (Altaff, 2015). Marine algae serve as a good source of protein for the fish. Low cost and good quality supplement feed provide essential nutrition and also a key demand for farmers to reduce the production cost. Due to the rising cost, uncertainty and unavailability of fish meal, it is an immense problem in modern aquaculture, especially in fish nutrition, to find a desirable replacement of fish meal. One of such international ornamental fishes is Poecilia sphenops . Despite its ornamental nature its normal needs and feeding pattern are not reported strongly, there is no detailed study on this fish variety so many researches have concentrated on detailed study of this fish (Lovell, 2000). In this study black mollies (Poecilia sphenops) were reared in aquarium tanks and algal diet was formulated, that supported the growth and survival rate of the mollies. Halymenia dilata was selected as a potential fish feed since there is no study report on marine red algae so far. Fish feeds made up of algae are used for the ornamental fishes to maintain the quality of the fish and its health condition. To obtain a potential fish feed it is necessary to assess the antioxidant activity and the presence of active compound. Experiments were also conducted to study the growth and survival rate of the Poecilia sphenops using formulated algal diet. Materials and Methods Sample Collection Marine algae Halymenia dilata was collected from the coastal area. The collected sample was cleaned and dried then grinded into very well powder. The algal fish feed was prepared with suitable composition and was fed to the ornamental fishes Poecilia sphenops (Black Molly). In order to study the potential of fish feed the pure algae were subjected to Soxhlet extraction method and then the extract was evaporated. The remaining extract was stored for future use. DPPH Assay Screening for antioxidant activity was done by using DPPH assay. Based on the protocol described by Von *Author for correspondence : E-mail : amthulazeez@gmail.com