In aquaculture, good production is attained by maintaining good growth, high survival rate and good fish condition and appearance. This could be achieved with good aquaculture practices, good feeding regime and maintaining healthy stocks. The water in which the fish lives contributes significantly to the overall health and well-being of the fish. Furthermore, presence of pathogens including fungus, bacteria, virus and parasites could bring harm to fish stocks and disturb the system. Regular monitoring of water quality and daily assessment of fish condition could help fish growers prevent further imbalance in the system or possible infection if there is, which could lead to disease and even death and massive fish kills. Although prevention is always better than cure, fish farmers also must be knowledgeable about the specific treatment to a specific fish disease just in case.
The following practices must be observed to make sure fish stocks are healthy:
In checking fish condition, which must be done daily even during feeding time, look for the following common signs of unhealthy fish:
It is most likely due to the environmental condition if significant number of fish are showing signs of stress or disease. Levels of ammonia, nitrite, pH, dissolved oxygen and temperature must be checked, immediately and respond accordingly.
Overfeeding and high fish density could lead to higher ammonia level if aeration system is not enough. However, in aquaponics ammonia are converted to nitrate and used up by plants to grow. Thus, if balanced number of fish and plants are maintained as well as correct feeding practice is observed in fish, ammonia and nitrite poisoning is not much of a problem.
Signs of ammonia and nitrite toxicity:
In aquaponics, pH should be monitored strictly and must be maintained between 6.4 – 7.4 to be tolerable for fish, plants and the nitrifying bacteria.
Signs of pH stress in fish:
Here are some of the most common pathogens in aquaculture. Familiarize yourself with them as they become critical to growing healthy and efficient fish.