Over the course of the 7 days while in country, I was able to oversee the addition of a 2nd fish pond at Chitipi which should double production and allow for growing catfish in a separate pond.
The 2nd pond was made with a combination of 19ft x 29ft 10mil heavy duty tarp brought from the USA along with 2 roles of 1.8m x 50m 250 micron plastic paper purchased from Lilongwe town outside of Polypack Plastic. We bought from men who imported from Zambia rather than polypack because polypack did not have any in stock (manufactured in Blantyre).
The plastic paper was melted together to form seems and was placed over top of the tarp in a small 5m x 7m pond which was dug by hand. We drained the concrete pond and I inspected for cracks. There were 3-4 cracks on the walls of the pond but since the pond was holding water and that the cracks were not too large, I recommended not trying to repair at this point but instead waiting at least 1-2 more years. If you try to repair, there is always the risk of causing more stress and cracks to the wall. The concrete pond is holding water very well after 2 years of operation with minimal algal growth and biofouling on the bottom. Upon draining, there was an estimated 100-300 fry sized tilapia (1-5 g each). There was at least 45 larger 50 g tilapia which we transported to the plastic pond and allowed to remain a few days to ensure they can live there without problems (sometimes plastics have poisons). We purchased another 2 rolls for a future 3rd pond, which was completed by solely by Geoff’s team after Jake left. We also purchased 15 fruit trees which will be planted near the fish pond to utilize water which is occasionally drained (once a week per pond). We also had an area groomed for planting vegetables.
Along with training students and staff on how to make a fish pond using the plastic paper (which is about 1/10th of the cost of concrete), I also did a demonstration on how to use drip irrigation to increase value of the farm and specifically using the water from the ponds to irrigate. The pond water has a very high nutrient load from the manure which is added along with the fish feces. This water can increase crop yields by 150 – 200% if applied correctly. This gives the farm the opportunity to grow crops during the winter time which can significantly increase the value of the farm and of that area. One pond has the capacity to grow about MK 100,000 – 400,000 worth of tomatoes per year if irrigated correctly compared to the value of 120 kg of fish generated per every 9 months valued at 480,000 MKwacha (MK4000 / kg). A proper business plan and trial should be conducted to understand the possibilities. In the past two years, Chitipi has harvested fish twice which is similar to other fish farms across Malawi 9-12 month harvest cycle. On the last harvest in March 2017, they harvested around 600 fish at an average mass of 75 grams for a total harvest yield of 45 kg. While it is recommended that fish be harvested before they reach their maximum size of 250 grams, harvesting while the fish are still small is up to the market. When we went to the market to price out the tilapia (chambo) taken from the lake, they were selling larger 200g fish for around MK 3600 per kg while for smaller 50g fish they were selling at around MK 5100 per kg. This was very surprising yet was probably a result of fish sellers taking advantage of people by increasing price of smaller fish. That being said, there does seem to be a market for small chambo in Malawi (50-100g), whereas elsewhere in the world it is generally market size at 250 g – 1kg.
With the addition of the 2 plastic ponds, I recommend the following scheme.
Plastic pond 1) 5m x 7m: stock with 500 catfish fry per year. Fertilize pond with chicken manure at 2 kg per 2 weeks to maintain green water. Feed fish with 50% maize bran 50% sunflower cake 1-3 times a week at 5% body weight. Add supplemental juvenile or fry tilapia from other ponds occasionally at 1-5 x per month. Catfish will eat the baby tilapia providing an excellent food source and allowing control of larger ponds.
Plastic pond 2) 5m x 7m: keep stocked with adult tilapia or ‘broodstock’. Fertilize pond with chicken manure at 2 kg per 2 weeks to maintain green water. Feed fish with 50% maize bran 50% sunflower cake 1-3 times a week at 5% body weight. When adults reproduce, count and use baby fish to stock larger concrete pond. Also, if the fish are continually reproducing such as during the warm season, harvest juveniles and place into catfish pond for food for catfish.
Concrete pond 1) 6m x 6m: stock pond twice a year with fish for a total of 2 primary harvests per year. Aim to stock pond in September or October with around 500 fry (1-5g fish). Fertilize pond with chicken manure at 2 kg per 2 weeks to maintain green water. Feed fish with 50% maize bran 50% sunflower cake 5 times a week at 5% body weight.