Pisciculture

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A pond in your backyard can raise a useful supply of fish. Raising fish under controlled conditions is pisciculture which has been practiced for centuries in the Far East, where Japan today produces over 100,000 tonnes of fish a year. The USA, Norway, and Canada are also big producers. Visit Freshwater Fishes of the World [1] and get tips on care along with pictures.

Contents

Fish Species Commonly Cultured

Oreochromis and common carp are two types of fish which are cultured most frequently. Hardy and disease resistant, they are easy to reproduce and fast growing under proper conditions. Oreochromis are of African origin though they have now been introduced to several countries around the world. They grow best in warm water (30° C to 35° C). Five tilapia species are commonly cultured. Oreochromis niloticus is the most widely cultured.

About 2000 years ago China was the first country where the first fish - the common carp, Cyprinus carpio - was cultured in ponds. These are temperate climate fish and thrive in water temperatures ranging from 1° C to 35° C. Since it was first cultured, several different varieties of common carp, with different scale patterns and body shapes, have been developed. Refer to FISH CULTURE MANUAL [2] for illustrative explanations on different aspects of fish culture.


Breeding Fish at Home

Breeding fish at home can be difficult, but once you know the tricks some fish species can live for a very long time, if proper care is given.

An enterprising Australian lady in Brisbane has demonstrated how it is easy to grow native fish successfully using water from a home rooftop. Much of the fish food can be home-grown earthworms and insect larvae. The project has shown how Australian native fish could be reared in a small area on worm-farmed kitchen scraps. See here [3] for details

Tips for Breeding Fish at Home

Find out and keep yourself informed about the following

  • How big the fish will eventually become
  • Its preference for food
  • Requirement of water parameters, such as temperature, pH ranges, etc.
  • Can it co-exist with others
  • Is it among the prolific breeder species? If so, you need to plan for when the babies come.
  • Is it susceptible to certain diseases common to fish?
  • The fish tank nitrogen cycle.
  • How to feed the fish

Dos and Don’ts

  • Give fish enough space
  • Avoid direct sunlight as it causes the tank water temperature to rise
  • Put de-chlorinated tap water in the tank
  • Treat them to a variety of tropical fish food
  • Do not overfeed
  • Change tank water every week or at least every two weeks
  • There should not be wide fluctuations in the temperature of the water
  • Give more frequent small feeds rather than one large feed
  • Give medication after proper diagnosis of the disease
  • Remove any carbon in your fish tank filters before using medications because the carbon will remove medication that you add to your water.
  • Don’t leave the fish tank lights on all of the time.

Also refer to Fish keeping for beginners [4] for more details


Pond Management

Some basic practices required for management and maintenance of ponds are:

Keep unwanted fish out of the pond

  • Carnivorous and other wild fish can eat fingerlings stocked into a pond and hence should be removed from stocked fingerlings.
  • There should be proper mesh screen covering of the pond water inlets to prevent entry of wild fish. Screens should be inspected daily and cleaned, if necessary, to prevent clogging. Before re-filling the ponds and stocking new fish, it should be completely drained and dried. Use poison to kill all remaining fish which could not be drained out. See Tropical Fish Tanks [5]

Lime and fertilize the pond

  • Natural fish food organisms are normally abundant in greenish colored water which indicates the presence of phytoplankton and other natural food organisms. Liming and fertilization increase organism. Lime, however, is necessary in ponds whose soil or water is acidic. Tests should be carried out in laboratories to determine whether liming is required as this can save a farmer time, labor and expense.
  • It is not true that fish require continuous flowing water. Fresh water is required only when there is the need to improve water quality or for replacing evaporation and seepage. Excess water flow washes out fertilizer nutrients and inhibits plankton growth.

Stock the right number of fish

The number of fish stocked into ponds should be just enough to ensure good growth and yield. Both overstocking and under-stocking can have adverse effects. The former slows down growth as the ponds get crowded. With under-stocking the natural food organisms in the pond cannot be utilized properly and this results in low fish yield. Proper stocking rates for tilapia range from 1 to 2 fish per m2 of pond surface area. Common carp are stocked at 1 to 2 fish per 10 m2 of pond surface area. During supplemental feed the higher stocking rate is used for both tilapia and carp. Stocking more than 2 carp per 10 m2 will cause the water to become muddy as a result of bottom feeding activity.

Feeding the fish

Fertilized ponds provide faster growth to fish than when they are provided with supplemental feed. Supplemental feeds include rice bran, wheat bran, corn gluten, African palm seed meal, dried and ground leaves from mulberry and ipil-ipil trees and manioc plants, dried blood, chopped earth worms, termites, chopped snails and insects. Two daily feedings (morning and mid-afternoon) are suitable under most situations. The feed depends on the stocking amount in the ponds and the average weight of the fish. Fingerlings normally require 10 to 12 % of their body weight. The feeding rate is gradually reduced to 2 to 3 % of body weight by the time fish reach market size. See Fish breeding [6]

Water Management

Fish can die of asphyxiation if it consumes too much oxygen. Ponds which are given large quantity of fertilizer and/or feed must be closely monitored to ensure satisfactory oxygen levels. Low oxygen occurs most frequently just before sunrise. Ponds should be checked early in the morning to find out if fish are suffering from low oxygen.

References

  • [7]
  • [8]