Early larval development and identification of infectious microbes and antibiotic resistance in hybrid climbing perch, Anabas sp.

Anabas species is a freshwater fish which has high potential of becoming a commercial species in Malaysia. It has high market demand due to its rich protein content. The main purpose of this study is to study the effect of environmental parameters on hatching period, egg yolk absorption period and starvation period during early development of hybrid Anabas species. Secondly, to isolate and identify type of bacteria exist on infected hybrid Anabas species. Thirdly, to characterize antibiogram of bacteria isolated from infected hybrid Anabas species. Matured broodstock were injected using pituitary hormone to induce breeding. The development stages of embryos and larvae were recorded over period of 0 hours (fertilization eggs) until 312 hours. The larvae and embryo development were studied in four different environmental parameters, namely, water temperature, pH, salinity concentration and formalin concentration. The early development was directly observed and documented in embryonic phase and larvae phase. The growth during embryonic phase was separated into eleven stages starting from a fertilized egg to cleavage, morula, blastula, gastrula, embryonic body formation, optic vesicle and auditory vesicle formation, blastopore closing, tail formation and hatching stages. The hatching further undergoes organogenesis until appears like their parents. Larvae phase consists of two stages which are pre-larvae and post larvae stage. Data analysis using one way ANOVA revealed that temperature is an important and statistically significant factor on hatching period (p<0.05). Result on pH, temperature and salinity concentration also gave statistically significant effect on egg yolk absorption. Meanwhile, results on starvation period indicated that temperature, formalin concentration and salinity concentrations were significant. Investigation on antibiotic resistance on infected hybrid Anabas species was done for 19 types of antibiotics using disc diffusion method. Aeromonas sp. and Salmonella sp. were isolated by using medium differentiation followed by a chemical test to identify the type of bacteria. The study reveals that isolates bacteria of Aeromonas sp. has lower Multiple Antibiotic Resistance (MAR index = 0.19), compared Salmonella sp. (MAR index = 0.21 and 0.22). The results on antibiogram showed that Salmonella sp. has lowered sensitive cases (59.5%) compared to Aeromonas sp. (67%). The findings in this study are important to conserve and improve management of Anabas species due to limitation of fish supply.