RESULTS
The trial on microalgal and cyanobacterial live feed had a significant effect on the size [length (cm)] of P. monodon.
The highest increase in mean length was generally observed after 20 days of shrimp growth, and the highest
mean length of 4.8 cm was achieved on the 30th day offeeding by Chlorella sp. (LF-1) (Figure 1).
The results show that addition of live algal food supported the growth of the juvenile of shrimp P. monodon. The lowest mean length of 4.1 cm was observed with LF-2 (Tetraselmis sp.).
Shrimp juvenile fed with LF-1 had significantly greater length (p < 0.05) than that of shrimp fed with
other diets. Similarly, weight of the shrimp was also higher with diet LF-1 (0.592 g fresh weight) and lower
with diet LF-2 (0.44 g fresh weight) after 30 days.
The mean weight of shrimp fed with diet LF-1 was significantly greater (P < 0.05) than that of shrimp fed with the other diets (Figure 2). Tetraselmis sp. (LF-2) did not support the growth of shrimp (Figure 2). Phormidium sp. When used as the sole microalgal diet gave the highest survival rate (Figure 3) (diet LF-5). Maximum survival of 83.33% was observed in feed LF-5 at the 30th day, followed by LF-1 (Chlorella sp.) (77%).
All the other microalgal feedssuch as Tetraselmis sp. (LF-2), Isochrysis sp. (LF-3) and
Synechococcus sp. (LF-4) showed poor survival (Figure 3).
The range in water quality parameters during the study is given in Table 1. The fluctuation of temperature, pH
and salinity was very low in all the experimental tanks.
Variations in DO, nitrate, ammonia and sulphates were also recorded. Low level of DO was recorded in LF-2
(Tetraselmis sp.) tank and maximum DO was observed in LF-3 (Isochrysis sp) tank.
Nitrate concentration was low in LF-1 (Chlorella sp.) tank and higher in Phormidium sp.(LF-5) tank. Ammonia level was high in LF-3 (Isochrysis sp.) and was low in LF-4 (Synechococcus). Sulphate was
high in LF-3 (Isochrysis sp.) tank and low in Chlorella (LF-1) tank (Table 1).
Observation of the proximate composition of juvenile shrimp carcass after the experimental period is shown in
Table 2. There was a significant variation in percentage of edible flesh of juvenile shrimp fed with all type of microalgal diets, but there was no significant variation in total body protein.
Crude lipid in the juvenile shrimp fed with diet LF-1 showed significantly higher value.
Ash content of the shrimp was lowest in shrimp fed with diet