The following steps are essential for a successful harvest:
Plan early to avoid surprises and do not let your customer down; give honest and accurate information. This way you will make good money and have customers for the next harvests.
Step 1: Calculate all your costs and make sure you don’t sell your fish below that price. Calculate all your costs in Kg of fish or per piece.
Step 2: Find a market. You could talk to hotels before to notify them that you will harvest. Give them the following information: size of fish and quantity, number of fish, location and conditions of sale, including price. You could take a sample fish for them to taste/see.
When you say you will harvest on Wednesday, do not change the date unless the client wants to.
Step 3: Stop feeding the fish one day before harvest
Step 4: Prepare the tools and labour for harvesting; this includes repairing holes in the seine net. You will need: plastic buckets, seine net, weighing scale.
Step 5: Reduce the water level in the pond; this makes it easier to harvest the fish.
Step 6: Harvesting is preferably done very early in the morning. While harvesting, handle the fish with care to avoid damages and post-harvest losses.
Step 7: If you bring fish to the market put the fish on ice.
Step 8: If there is a market for value added fish (e.g. deep fried, or gutted) then include all your costs in the price calculation
The exact time for harvesting will be determined by the market (the preferred market size for fish, and opportunities to achieve good volume of sales and good prices (for example, Fridays, civil service pay days, Christmas time etc.).
When you harvest tilapia, you will have different sizes. Each size has a specific market.
There are two types of harvest: partial harvest, and complete harvest. A partial harvest can be done using a seine net or a cast net, but for a complete harvest, the pond is seined 3–4 times and then drained to get all the remaining fish.
Fish should not be fed the day before harvesting so as to improve the survival rate of the fish during handling.
Two weeks before a complete harvest, the application of fertilisers should be suspended.
It is advisable to harvest early in the morning when the pond water is still cool while the pond is emptied. This will reduce fish stress as they are being seined or collected.
All equipment needs to be prepared in advance: for example, inflow of clean water, holding tanks or hapas, buckets, seine nets, scoop nets, cast net etc.
For maximum utilisation of your pond, a full harvest is recommended. There are several good reasons also to do a partial harvest such as:
If the pond was overstocked
You’re lacking adequate water
The market cannot absorb all your fish at once or
You have an order that gives you a very good price.
The harvesting can start at about 3 to 4 months after stocking the fingerlings, or when the fish are big enough to eat (200–300g size). Partial harvests can be continued until the fish have been in the pond for 5–7 months, or until there are only a few left.
Complete harvest requires draining the pond and means the end of a production cycle. The pond should be drained partially very early in the morning of the day of the harvest. To speed up the harvesting process which could be stressful to fish, seining is carried out while the pond is draining. Screen your outlet pipe to prevent fish from escaping.
A seine of 1–2cm mesh size with a height of 2–3m is commonly used. For every 2m of pond width, 3m length of seine net is needed.
The seining should begin in the shallow end of the pond and work towards the deep end. The seine should be stretched from dyke to dyke and hauled gradually. It is important to work carefully so as to disturb the pond bottom as little as possible. Scoop nets should be used to move fish from the seine to buckets on the pond bank. Even with several people, a harvest of more than 40% of tilapia per seine haul is difficult.
Transporting fish is a very delicate part of fish culture. Fry and fingerlings must be transported from hatchery to pond for stocking. Brood fish can also sometimes be transported into ponds. It may even be necessary to transport live harvested fish to the market for sale. Many methods for fish transport have been developed.
Fish are generally transported in containers such as cans of different sizes, pots made of ceramic or metal, wooden or metal buckets, vats, barrels, plastic bags, styrofoam boxes, bottles, and jugs. In fact, almost any clean, waterproof container may be used.
We consider two basic systems for transporting fish, the closed system and the open system. The closed system is a sealed container where requirements for survival are self-contained, for example a sealed plastic bag partly filled with water and oxygen.
The open system consists of water-filled containers in which the requirements for survival are fully or partially supplied from outside sources, for example a small tank with an aerator stone for long distance delivery of fingerlings or without an aerator stone for short distance (10–15 minutes) delivery.
Once fish have been placed in their transport container they are brought to their destination by the quickest means possible.
Fish survive transport better if they have no food in their intestines. For this reason, they should not be fed for two full days prior to the time they will be transported.
Fish can also be harvested and held in net enclosures or tanks for 24 to 48 hours with clean, preferably gently running, water. The fish pass food out of their intestines and will be in good condition for transport. If the fish have disease or parasites, they can also be treated easily in tanks prior to transport.
1.Water quality: the major parameters that limit loading density (kg of fish that can be transported per water volume), are adequate oxygen levels and the build-up of toxic waste products such as ammonia and carbon dioxide.
2.Temperature: as temperature increases, fish consume more oxygen and oxygen is less soluble.
3.pH: high pH makes ammonia more toxic; low pH makes carbon dioxide more toxic.
4.Loading density: the more the fish, the more the oxygen consumed and the more waste produced.
One Kg of large fish uses less oxygen than one kg of small fish. Make sure you adjust for size when deciding on loading densities.
5.Trip duration: even if oxygen is adequate, waste increases with trip duration.
6.Road quality: although bumpy roads make for some agitation of the water thereby increasing oxygen content, very bad roads cause the fish to toss around and they arrive at the destination very tired.
7.Fish health and condition: fish should have EMPTY stomachs. This reduces the pollution of the water from regurgitation and from elimination of wastes. Fish are cold blooded, and just like crocodiles, they can survive for quite a few days without food.