Lately reports have been received from farmers from different areas in regard to fish death . Some die at 2 months, 3months up to 5 months which is so painful looking at the resources spent on feed, fingerlings, water bills, effort and time. This has made many people to give up on their fish farming projects. However most of the fish kills is either high content of ammonia or low levels or no oxygen in the pond.
Ammonia may vary from pond to pond depending on the type of the culturing facility e.g poly earthen ponds, semi earthen ponds, earthen ponds, concrete ponds and tanks.
EFFECTS OF AMMONIA
Ammonia in ponds its as a result of excess feeds especially sinking feeds at crumble stage, fecal matters especially when the pond is over populated, organic manures when used directly e.g pig manure, grass, dry leaves and main more.
These mentioned above they settle at the bottom of the ponds causing the water contaminated at the bottom. During rain season due to water mixing all the water becomes contaminated such that they affect fish gills hence preventing them to uptake the oxygen from the water. Sometimes water mixing can occur at night when it’s too cold and the action can wipe out the all stock from the pond as if its poison leaving no live fish behind.
In earthen ponds Ammonia levels are not that high as compared to poly earthen ponds or concrete ponds.
MAIN CAUSES OF AMMONIA IN PONDS
1. Too deep ponds
2. Over stocking
3. Excess feeds
4. Organic manure
5. Bad feeding methods
1. Making ponds with recommended depth
2. Stocking right number of fish in relation to the right size of the pond.
3. Draining and refilling at least one or twice in a month especially when using pond liners.
4. Feeding from one position
For more information on Fish health,causes of death and solutions contact us on 0778840932 or visit us at number 3 Sandford Crescent Eastlea Harare