Brief Background
Vietnamese koi is getting popularized in Maharashtra state due to its higher market potential and high growth with attractive FCR. Koi has added advantage in aquaponics farming due to its higher tolerance to lower water DO, higher nitrate level and wide choice of feed (omnivorous feeding). Said trial was conducted during June 2018 to December 2018 at Vigyan ashram Aquaponics farm setup.
System details
Fish tank – HDPE lined fish tank of approximately 15000 lit with bottom drain connected to separate sludge tank.
Bio-bed- Bio-beds where constructed using lose brick structure & HDPE plastic liner with volume of approximately 7000 lit . Bio-beds were connected to each other by flood & drain based siphons system. Water was taken back to fish tank after circulating in bio-beds. Bio-beds filled with red earthen brick as bio-media and planted with Japaneses mint (Mentha spicata) & Alu / Taru (Colocasia esculenta).
Water circulation – Water from fish tank is taken out in separate sludge thank through bottom drain. Water from sludge tank is pumped to bio-beds with submersible sludge pump connected through automated timer. Bio-beds were connected to each other by flood & drain system to take water back to fish tank.
Water quality parameters- Water DO is maintained by fixing air pump (airflow of 35 Lit/Hr) with power backup system. Water DO was maintained around 6 to 7 ppm. Water ammonia (NH4 ) was maintained below 0.5 ppm by circulation through bio-beds. Water temperature was kept between 22 to 28 ° C by restricting evaporative cooling by covering bio-bed & fish tank with UV stabilize polyhouse paper.
Fish feed & feeding interval- Fish fed with 0.8 to 4 mm floating pallets with 28 to 32 % protein @ 10 to 2 % feeding rate during trial perios. Feed was given 4 times/day @ equal interval during day time. Fish were also fed with fresh azolla @ 500 gm/day (not taken into calculation of FCR).
Result –
Fish growth & FCR – Total of 800 fish fingerlings of koi and 40 yearlings (average 60 gm) of grass carp were raised during June to December period. The final fish density was 5 Kg / lit of water. Average fish weight achieved during 7 months raring was 53.75 gm with average length of 18 Cm / per fish. Total of 73 Kg fish were harvested at end of trial with FCR of 2.01 (147 Kg fish floating pellet feed used).
Market rate & Sales – Koi has good market potential. Fresh fish were sold @ 200 Rs/ Kg in Pune city as wholesale price.
Difficulties faced & way forward- Following were some of the difficulties faced during trial –
- Fish mortality- Very heavy (almost 80 %) fish mortality was faced during trial. Its was mainly higher stress levels due to high stocking density leading to fungal infection. Its been also observed that Koi has very strong cannibalism nature. During course of experiment separate trials were conducted to standardize stocking density of koi fingerlings & treatment methodology so as to avoid these issues in aquaponics farming. Experiment results available on – https://vigyanashram.files.wordpress.com/2019/01/fish-trial-paper-i.pdf
- Un-even growth of fish- Its found that koi has very high degree of un-even growth rate. It may be due to aggressive nature of healthy fingerlings. Its found that in aquaponics separation (sizing), selective feeding etc may need to adopt for even growth & harvesting.
- Water losses & pump failures – Failure of water pump, electrical failures and leakages in bio-bed, fish tank were some of the frequent issues during trial. Its affected overall water quality parameters mainly higher ammonia concentrations during later stage of trial affecting overall growth rate & FCR.
Its found that Koi has good potential for aquaponics farming due to adaptability of lower quality water parameters, higher tolerance and market potential but Koi farming is also bit tricky due to its strong cannibalism nature. Aquaponics farmers can adopt koi with very good returns provided they got enough knowledge & skills in koi handling with market demand study.
Vigyan Ashram(DST Core supported) Blog 