Breeding and Culture of Tilapia

INTRODUCTION

Tilapia are endemic to Africa, but interested in their aquacultural potential led to nearly worldwide distribution within the past fifty years. Initial enthusiasm was based on characteristics that made tilapia appropriate for subsistence fishfarming in developing countries. Several species are herbivores, readily reproduce in small ponds and are highly tolerant of poor water quality. Interest in commercial production of tilapia was initially dampened by a small harvest size resulting from excessive reproduction and stunting. Within the past twenty years, however, commercially viable techniques have been developed to control overcrowding in ponds, thereby permitting growth to larger sizes.

Feeds and Feeding

Under natural condition, tilapia is predominantly a herbivore and a detritus feeder. This means that, they can produce high quality protein, suitable for human consumption, from less refined protein sources.
 

Generally, tilapia of the genus Oreochromis are primarily omnivores taking phytoplankton, periphyton or detritus. Some of the genus Tilapia tend to take coarser food including macrophytes. Consequently, they are used to control weeds in irrigation channels, ponds and dams.
 

Pond Management

Fertilization
 

Fertilizer stimulate the growth of plankton, which is the natural food of fish. Hence, fertilizers increase fish yields three to four times. Pond fertilization maybe appropriate if the following indicators are observed: measurements indicates low levels of nitrates and phosphates.

Fish stocking density

Fish stocking ration is one of several factors that affect fish growth. At low stocking density, the amount of natural food in the pond is higher for each individual fish and the excess food is not utilized. As long other factors are not limiting, the growth of fish per day will be better. However, the growth of fish will slow at higher density stocking because the capacity of the natural food to support the fish population will be limited to a certain extent. The maximum physiological growth of tilapia is attained at low stocking density.

Aquatic Weeds 

Generally, aquatic weeds are abundant in freshwater ponds. However, a well-managed culture pond should not have weeds floating aquatic plants at all.

Predation and other pest

Some pest and predators commonly affect fish production in ponds. Predators are organisms, which prey on the fish being cultured and the animals that compete for food or space are called competitors.

Supplemental feeds

Supplemental diet as a prepared diet formulated to provide protein and other nutrients besides those obtained from natural food organisms in the water. As the fish grow, the natural food in the pond will be insufficient to sustain the growth of the fish population. Hence, the growth rate will be less than the maximum potential. As the food deficit increases, growth rate decreases.

Water Quality Management 

Water quality management is one of the most important factors in insuring a healthy fish population. Water quality in the aquatic environment considerably affects the growth and reproduction of fishes.

If the water quality is beyond tolerable limits. It will adversely affect fish health. Therefore, the design, location and operation of a fish farm are very critical factors to be considered in constructing a fish production system, be it a fishpond, a hatchery, a fish cage and the like.

Land-based Hatchery

Earthen pond method

The earthen pond hatchery is the simplest and most common method of fry/ fingerlings production. Ponds serves both as spawning pond and rearing pond.

Selection of site
 

Water source- Irrigation deep/ shallow well Ground water spring production.

Water Quality- Year round supply

Soil types – Clay, clay loam sandy loam

Topography – Slightly sloping flat

Flood hazard free

Accessibility to farm supply/market

Peace and Order situation

Availability of labor

POND PREPARATION

Pond draining- drain the pond completely and collect all unwanted fish and eliminate predators and other unwanted species

Eradication of predators

Levelling of pond bottom

Installation of screen and gate boards

Water intake 1 m.

Fertilization during preparation (basal application)

Chicken manure 2,000kg/ha.

16-20-0 @ 100 – kg/ha.

BROOD FISH STOCKING

SELECT Breeders based on the criteria mentioned

Stocking rate 100-200 kg/ha or 2-4 pcs/sq m. @ 50-2000 g is recommended

Sex ratio 1:3 (male to female)

FEEDING

Fish will be fed either with formulated diets or commercial feed available in the locality

Supplemental feeding should be done if manure is not applied in the pond. However, If high manuring rate are used, feeding of the broodstock may not be required.

Feeding rate 2-3 % BW/day

Feeding frequency 2 x a day

COLLECTION OF FRY

The fry should be collected with a scissors net at interval of about three weeks to one month. The collected fry should be transferred to nursery hapa for rearing and grown to fingerlings stage or disperse directly. Fry should be fed a diet in powdered form at the rate of 10-15% BW/day. Feeding frequency 4 x a day

CONDITIONING OF FINGERLINGS PRIOR TO TRANSPORT

The collected fingerlings should be collected in hapas or tanks for conditioning 3 days or more before dispersal. During conditioning period, the fingerlings are given supplemental feeds. Feeding must be stopped 24 hours prior to dispersal/transport. Ideal stocking rate 70-80 kg. @ 1.5 x 10 x .95 m. tanks & 15-35 kgs fish @ 3 x 3 x 1.5 m. hapas Production cycle 30 days.
 

TILAPIA GROW – OUT MANAGEMENT SCHEME
 

EXTENSIVE

SEMI-INTENSIVE

INTENSIVE
 

Stocking

Feeding

2 pcs / m2

No feeding but with fertilization

5 pcs. / m2

Supplemental feeding and fertilization

10 pcs. / m2

Commercial feeds no fertilization and with good aeration

POND MANAGEMENT
 

Fertilization

Feeding

Entrance of undesirable fish species in one pond

Aquatic weed control

Water quality monitoring

Record keeping

Harvesting and M<raketing

How to Avoid OVERCORWDING?

Manual collection

Manual sexing

Stocking of predator

High density effects

Cage culture

Hybridization

Tilapia Sex Reversal

GMT, GIFT, EXCEL etc.

Measures to Prevent Fish Kills due to poor water Quality

Visual survey of the water

Change from green color to gray indicators die – off maybe occurring

Scum appearing to the surface indicators low D.O. level

Fishes gasps for air on the water surface

Secchi disk visibility

Visibility less than 30 cm indicates phytoplankton bloom