Nutrient-enriched live lobster cockroach, Nauphoeta cinerea, enhances growth and pigmentation of the pearl arowana, Scleropages jardini

Abstract This is the first report on the use of live cockroaches as feed for farmed arowanas. Firstly, the nymphal development period, reproductive potential, longevity and nutrient profiles of the various development stages of the lobster cockroach, Nauphoeta cinerea , were determined. The fecundity of each female cockroach averaged 82.9 nymphs. An increase in body crude protein and lipid levels was observed as nymphs metamorphosised into later instars. The nutrient content of the adult stage was different from the nymphal stages with distinct differences evident between sexes. Secondly, in the feeding trial of pearl arowana, Scleropages jardini , three groups of live cockroaches were used; adult males with low lipid and high protein levels (3% and 30.1%, respectively; A-LLHP, control group), adult males with mid-level lipid and high protein levels (6.1% and 29.7%, respectively; A-MLHP) and late nymphs with high lipid and lower protein levels (10.3% and 22.9%, respectively; N-HLLP). Each group of cockroaches was fed to eight replicate individually-housed fish once daily for 12 weeks. A-LLHP and N-HLLP cockroaches were fed a commercial rat feed, whereas A-MLHP cockroaches were fed a specially formulated feed with added astaxanthin (80 mg/kg) to produce nutrient-enriched cockroaches. Arowana growth was highest in the N-HLLP-fed group followed by A-MLHP and A-LLHP ( ). The best feed utilization efficiency was observed in the N-HLLP group. Intraperitoneal fat and muscle lipid content was significantly higher in fish fed the nymphs than those fed adult cockroaches. Scales of arowana fed A-MLHP cockroaches showed the highest melanophore and xanthophore counts. Xanthophores were not present in the scales of the N-HLLP group. Late nymphal stages are optimal for growth enhancement and adult cockroaches for pigmentation of fish. This study showed that live cockroaches can be nutrient-enriched to enhance arowana growth and pigmentation.