The effect of Biofloc and aquaculture systems on growth and production of LIZA CARINATA

Abstract

This study was carried out to evaluate both the suitability of biofloc system condition for cultivation of Keeled mullet (Lizacarinata) fish. So, the best growth performance and production of Liza carinata under two different culture systems with the highesteconomic value was investigated. Three experiments were designed for this investigation.

The first one was consisted of 2x2 factors experimental arrangement of two levels of crude protein (23 and 28% CP) and two culture systems (clear water system (CWS) change and biofloc treatment (BFT) with zero water exchange). The results indicated that fish fed on 28% CP had significantly higher FBW,

FI, EG and ER values compared to fish fed on 23% CP. Fish reared under biofloc treatment recorded the highest ∑ω3 levels in

their whole body, compared to fish reared under CWS system. It could be concluded that biofloc technology is suitable system for

Liza carinata cultivation.

The second experiment was carried out to study the effect of fish density on growth performance of Liza carinata. For this purpose six (6) hapat with equal area 1m2 were put in one of the pond's farm. Each two hapa were stocked with one of the chosen density; 15, 20 and 25 fry /m2 named as D1, D2 and D3, respectively. The highest FBW, ADG, SGR and EG were recorded in D1 group followed by D2 and D3 the best feed utilization value (FCR, PER, PPV and ER) were recorded for D2.

ω3 fatty acids recorded highest value in D1 followed byD2 and

D3.

The third experiment was carried out to study the effect of mixed and polyculture system on growth and production of Lizacarrinata. The first group of hapa was stocked with 20 fry of Liza carinata only monoculture group (MG); the second group was

stocked with 14 Liza carinata and 6 Rhabdosargus haffara

(polyculture group1, PG1) and the third group contained 10 Lizacarrinata, 5 Rhabdosargus haffara, 5 Mugil capito (PG2) calledas MG, PG1 and PG2 respectively. The average initial body weight was 0.26±0.003g for Liza carinata. The best growth performance parameters were recorded in PG2, followed by PG1

and MG. The highest ω3 fatty acids recorded for MG followed by PG1 then PG2. A high ∑ω3/ ∑ω6 ratio value was observed on

MG. So, it could be concluded that biofloc system decreases the negative impact of fish farms on the environment and also improves the economic efficiency. Biofloc system is suitable for Liza carinata culture, and the obtained fish wass healthy as the∑ω3/∑ω6ratio were within the recommended UK values. Also,Liza carinata records the best performance under stockingdensity D2 and fatty acid contain differ under different stocking densities. Liza carinata record the best performance for PG2 while the best economic value recorded in MG.