How to Control Microbial Infestation in Fish Hatcheries

Viable Clarias catfish eggs


Fish eggs are highly nutritious organic substrate. They also carry an abundant microbial load, either as normal flora of fish or as pathogens. This makes them highly susceptible to microbial infestation through the incubation process in fish hatcheries.

Soon after eggs are fertilized and laid in incubating tanks to hatch, a rapid multiplication of microorganisms take place simultaneously, which if not checked, is capable of inhibiting the process completely. This is what causes the heavy offensive odor that wells up from incubating systems that are not adequately refreshed / managed.

Unchecked action and proliferation of bacteria in fish egg incubating and fry holding systems can raise ammonia and nitrite levels to lethal limits. Fish eggs also form a viable substrate for rapid growth of fungi during incubation. Especially unhatched fish eggs that habor heavy fungal loads turn out to be the first feed to which emerging hatchlings are first exposed. This, if left uncontrolled causes fungal infections in fish hatchlings, which eventually knocks them dead in the first few days after hatching.
This explains why many fish hatcheries lose a greater fraction of all hatchlings they manage to hatch.

Optimum water quality abundantly channeled into refreshing fish incubation and holding systems, is by far the most effective and healthiest way to prevent those complications.

However, where stubborn infectious microbes must be eliminated, a number of antimicrobial substances are employed. These substances must also be such that pose no threat to fish or human health, while they remain lethal to pathogenic microbes. Among such substances safely used to rescue fish hatchlings from pathogens are;

  1. Table Salt
  2. Hydrogen Peroxide
  3. Grape Seed Extract
  4. Methylene Blue
  5. Vinegar
  6. Gentian Violet
  7. Copper Sulphate, etc.

As preventive measure, these substances are also used at certain safe concentrations to disinfect fish eggs prior to laying then for incubation. This helps to slow down microbial infestation, giving hatchlings better chances of survival.

It is hereby recommended that fish hatcheries that find it difficult to raise hatchlings successfully, look first into getting all key water quality parameters within optimum limits. Microbial infestation can then be adequately tackled by abundant refreshing of incubating and fry nursing systems, or using any of the listed antimicrobials bin safe concentrations and routine.

We, at PiPAR Fisheries are available to offer you the needed technical assistance, should your fish farm or hatchery require consultancy services.
We are reachable, always, via our contacts available on this website and our various social media channels.


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