A senior lecturer of the University of Peradeniya said recent reports of death of fish in the Kandy Lake was due to the over population of fish, low oxygen levels and multiplication of parasites through waste water introduced into the lake.
Dr. A. Arulkanthan, Senior lecturer and Co-ordinator to the Centre for Aquatic Animal Diseases, Diagnosis and Research Faculty of Veterinary Medicine and Animal Science of the University of Peradeniya said the deaths in hundreds are reported daily and there were no reports of mass mortality.
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| Pictures show members of the Faculty of Veterinary Medicine and Animal Science of the University of Peradeniya collecting samples of fish and samples of water from the Kandy Lake. |
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| A dead fish floating in the lake. |
“If it was a chemical pollutant there would be reports on mass mortality. But daily we see only hundreds of dead fish floating. Research carried out by our centre reveals the over population of fish can be one of the reasons causing the deaths”, he said.
He said as fishing was banned and most of the fish belonged to the ‘Thilapia’ variety which breeds fast, the fish had hardly any place to swim. He added even if 50% of the fish were removed from the lake it would not help to control the breeding.
“The parasite ‘Isopoda’ in the lake multiply when water quality is poor. The quality of the water depends on how many organic substances are collected in the lake.
Most organic substances develop from waste water dumped from households and hotels -mainly from the food items added to the waste water. These are also nutrients for the algae. In the night the algae and the fish compete for oxygen”, he said.
He said fish also died due to the low oxygen levels which caused brain and internal damage. “Parasites also damage the gills of fish thereby causing respiratory damage. Due to the blood levels coming down fish become anaemic. This aggravates the situation”, he said.
We have diagnosed this condition as Hypoxia caused by parasites and low oxygen levels.
He said the most effective way to control organic substances collected in the lake was waste water treatment.
“Instead of dumping waste water into the lake organisms should be removed and only clean water should be pumped into the lake. However this is a long-term recommendation and the most effective one. Desilting mud and removing algae are some short term measures” he said. “We are however continuing with our research” he added.
Dr. Arulkanthan said an advisory committee consisting of members of the Centre, Engineers of the Irrigation Department, experts from the Water Board, representatives from the Kandy Municipal Council and the Government Agents’ Office were in the process of preparing recommendations which would be submitted within a month’s time. |
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