Lesson from www.fishclass.icu

These are Tanks where the larvae are nursed to fry and finally to fingerlings. Small Aquaria, plastic containers, basins, concrete tanks and fibreglass tanks etc could be used for this purpose. When the larvae have been acclimatized in the larval rearing trays for about 10 days and initial feeding started, they are further separated into other units of various sizes and proper feeding carried out.

Within such systems, the farmer watches out for 'jumpers' (those that quickly outgrow their age mates) and ensures that they are immediately removed from the crowd and kept in separate tanks where those of their sizes are. Failure to do that promptly will result to cannibalism of the smaller ones by the bigger ones. Thus regular sorting takes place in the nursery Tanks.

If the larvae are reared outdoors in tanks, it is recommended that every two weeks, sorting should be carried out. Nursing Fish larvae in flow-through systems guarantees better growth and performance as contrasted with stagnant water systems. Aeration is equally important during this stage of larval production and the water quality should be monitored regularly since there are more metabolites being released as a result of increased feeding and metabolic activities.

If artificial feed is used, they should be of high protein content and of balanced nutrient including vitamin premix etc.

When hatchery tanks are newly constructed, they should be treated with alum ( potassium aluminum sulphate) if concrete, for one week or filled with either fresh water or salt water to attain neutral pH of fibreglass.
After breeding for operational hatcheries, disinfections with 12% sodium hypochloride solution at 200ppm for 24h should be carried with proper cleaning up.

The salt water or fresh water to be used should be filtred except when borehole water is used. The system should be aerated adequately. In fact, higher aeration is usually required in both spawning and hatching Tanks. Most importantly, the physicochemical properties of the water must be monitored regularly.