What is needed in a hatchery

BY Leslie Ter Morshuizen

A fish hatchery is a specialised environment providing the perfect setting to prepare the adult breeders, spawn them, incubate the eggs and successfully complete the early rearing phase of the fingerlings.  The aim is to reliably produce the required quantities of fingerlings that are healthy and fast growing, either for sale to other farmers or to rear within your own growout facilities.
The genetics of the breeders is the first consideration.  Line breeding is required to optimise desirable traits over generations, but this needs to be balanced against inbreeding whereby resilience is lost due to the concentration of certain genes resulting in the undesirable decrease of others.  Parent fish need to always be of the best possible genetic stock which have been selected for their fast growth, good yield and disease resistance.
Broodstock feed needs to be of a high quality such that the breeders can produce quality eggs and sperm.  The nutrients packed into the egg by the female is the only source of nourishment available to the egg during incubation and whilst it uses its’ yolk sac prior to feeding externally for itself.  Feed for the breeders must therefore include all the necessary minerals and vitamins.  Live feed is most useful in ensuring healthy breeders.  The newly hatched fry grow extremely quickly often increasing their body mass by 1 000 times during the first 30 days!  Fuelling this growth requires frequent meals of the correct type, quality and quantity of feed.  In many species, live feed is essential for the early fry stages, with brine shrimp playing an especially important role.  Micro-pellets may provide a near-adequate replacement for live feeds but these are generally unavailable in Africa at this stage.
Water quality for the breeders and the offspring must always be pristine.  Metabolites such as ammonia should be at low or undetectable levels, dissolved oxygen should be at saturation, and the temperature and pH appropriate for the species being bred.  Fry are especially sensitive to adverse water quality, with both survival and growth rate being partly a function of water quality.
Lighting is important for the staff working in the hatchery to be able to manage this facility to a high standard.  However, in certain species, lighting is even more important for the breeders than the staff, as the breeders require appropriate day length and light intensity to prepare them for spawning and for the act to occur on queue.  Fry often required subdued lighting initially, but once they are free swimming and feeding well, the lights can usually be turned up to facilitate easier management.
Small fish are sensitive to health related issues and breeders fighting infection are unlikely to reproduce reliably.  It is therefore vital to keep the hatchery free of pathogens, both through quarantining the breeders before they are brought into the hatchery and through maintaining a bio-secure environment.
Attention to detail is the hallmark of a successful hatchery operator, in order to produce reliable quantities of good quality fry we need to watch these variables very closely.

 November 26, 2017
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