Identification of larval and pre-juvenile development and effects of different feeding frequencies on reproductive performance, pigmentation, growth and survival of mbuna cichlid species (Iodotropheus sprengerae, Maylandia lombardoi, Melanochromis auratus, Pseudotropheus demasoni)

The largest group of living groups exhibited in aquariums are the cichlids. Especially mbuna species found in Lake Malawi represent a large group which are increasing the numbers each passing day. In this study, larval and prejuvenile development stages and the effects of different feeding frequencies on growth, reproductive performance and pigmentation of four mbuna cichlid species were investigated. As study material, kenyi (Maylandia lombardoi), rusty (Iodotropheus sprengerae), auratus (Melanochromis auratus) and demasoni (Pseudotropheus demasoni) cichlid species supplied from a commercial facility (İstanbul, Turkey) were used. Experiments were carried out in Yalova University Armutlu Vocational School (Yalova, Turkey). Eggs and fries were taken from buccal cavity of females and they were stocked to artificial breeding containers. Then, larval development stages were photographed under the stereo microscope. Five experimental feeding groups have been formed including every other day (2G1), one feeding daily (G1), two times a day (G2), three times a day (G3) and four times a day (G4) for each species in feeding frequency trials. Fish were fed with commercial granule feed for 16 weeks with ad libitum. The study was carried out in freshwater recirculating system which has 100 L each tank and 15 fiberglass tanks with three replicates. Ten individuals with average 2 g body weight have been stocked to each tank in every trials. Growth performance were monitored biweekly by weighing and measuring total lenghts. For determining the reproductive performance, eggs were removed from buccal cavity of fish, and they were monitored over 14 days. The color measurements were performed on left surface of body area and caudal region of each fish for every 2 weeks. In larval development experiment, the start of the formation of the young draft has been seen after the cleavage, blastula, gastrula and pharyngula stages for all species at the end of the 16th day. Larval development has been lasted for 19 days for rusty cichlids, 20 days for auratus cichlids, 21 days for both kenyi and demasoni cichlids. In feeding frequency trials of kenyi cichlids, although final mean weights of two, three and four times a day groups were statistically similar, the best growth was observed in three times a day group with 11.16 g. According to reproductive performance, fertilization rate of three times a day group were greater than the others (P<0.05). In color parameters, the best lightness of body and caudal regions were determined at three times a day group (P<0.05). Final mean weights and final mean total lenghts of rusty cichlids fed with three and four times a day were statistically similar. For reproductive performance, mean seed production of three times a day group was superior than the others (P<0.05). Absolute fecundity and fertilization rate of four times a day group were higher than the others (P<0.05). Egg hatching rate and larva survival rate of three times a day group were greater than the other groups (P<0.05). For coloration, although there is no statistically differences between ligthness of body and caudal regions, the best values were observed at three and four times a day groups. The spesific growth rate and feed conversion ration fed with four times a day of auratus cichlids were superior than the others (P<0.05). In reproduction, mean seed production of three times a day group was statistically superior (P<0.05). At color parameters, the b* values of body and caudal fed with four times a day were greater than other groups (P<0.05). Spesific growth rate and feed conversion ratio of demasoni cichlids fed with two times a day were statistically higher than the others (P<0.05). Survival rates of one daily, two and three times a day groups were similar and 100% (P>0.05). In reproduction, absolute fecundity of two times a day was greater than other groups (P<0.05). For coloration, the b* value of caudal region fed with two times a day was superior than the others (P<0.05). According to these parameters, the ideal feeding frequencies have been determined for three times a day for kenyi cichlids, three or four times a day for rusty cichlids, four times a day for auratus cichlids and two times a day for demasoni cichlids. In conclusion, implementation of determining feeding frequencies for commercial production of these species is thought to be caused the positive outputs for both producers and aquarists.