Professor Hout Vutha, vice dean at the Faculty of Fisheries at the Royal University of Agriculture, has specialised in aquaculture since 1991. The problems Leang Roath expressed with his aquaculture are known to the professor and he has some solutions.
“Water quality is very important in aquaculture,” the professor said, adding: “If there are a lot of fish in the pond, enough fresh water has to be pumped in and out.”
The aquaculture specialist explained that water quality also depends on the type of fish in the pond. He gave an example: “Striped catfish can survive in dirty or turbid water, while Nile tilapia and silver carp need clean water.”
Clean water, however, is not to be confused with tap water but water with enough oxygen. “When we see green water it doesn’t mean that the water is dirty. It can look cloudy from plankton,” Vutha said.
In terms of fish food, the professor said that fish pond owners have to think about quality rather than price if they want their fish to grow faster. “We have to understand that some food is expensive; the protein level is higher which makes the fish grow faster.”
He added that fish breeders could also mix the food by themselves but must first understand the right doses of vitamins and other nutrients.
Plankton is also a good food for fish, but again the type of plankton fed has to match the type of fish. “Fish like striped catfish are carnivorous so they need animal plankton, while fish like Nile tilapia and silver carp feed on plants so they need both animal plankton and plant plankton.”
Though plankton can be a good food source for fish, pond owners have to make sure to stay in control of the plankton growth in the pond. “At day time, the oxygen created by plankton increases, but at night oxygen levels drop,” he explained, adding that “at night, the plankton absorbs the oxygen and releases carbon dioxide into the water, which is poisonous to the fish.”
To Roath’s concern about protecting fish from being caught by other people, the professor said he was not in a position to comment on the problem saying that “it’s the responsibility of a pond owner”.
With enough water resources already available in the country, Vutha recommended Cambodian people, especially farmers, start breeding fish on their rice farms as well. “My message is to suggest that they breed fish in their existing farms,” he said, concluding: “It is always very important to find ways to fight poverty in the countryside.”