ABSTRACT

Live preys' availability to larval fish is determined on the basis of suitable size, frequently described as gape width/prey size proportion (Dabrowski and Bardega, 1984). In some cases, larval freshwater fish, like the 4-5 mm total length yellow perch (Kolkovski and Dabrowski, 1998), eat prey smaller than 50-100 µm in width, whereas in the case of the first feeding larval walking catfish (Clarias), the largest size of Artemia nauplii offered, 205-295 µm (4% of fish body length), increased the growth, but compromised survival in comparison to ungraded size nauplii. Nauplii

graded into two categories-below 59 µm and 59-183 µm, mesh size n e t — even when fed in excess, resulted in much lower fish size and survival was 14-28% in comparison to 67% in fish fed with unsieved Artemia (Petkam and Moodie, 2001). Therefore, it is important to readjust the feed particle size (live or inert) to the optimum acceptable size of larval fish.