Nairobi — Kenyan legislators on Wednesday contested the government's position on the widespread death of fish in Lake Naivasha saying only a full probe by one of the departmental committees will unearth the truth behind the catastrophe.

A preliminary report into the deaths had blamed depletion of oxygen in the lake.

Fisheries Minister Paul Otuoma told the House that another report from the Kenya Plant Health Inspection Service will be released on Friday. The Kephis report, the minister said, arises after examination of the tissues in the dead fish.

The contest over the preliminary report was further aggravated when John Mututho (Naivasha, Kanu) claimed that the fish died due to poisonous effluent from the sewage system of Naivasha Municipal Council and a flower farm.

Mr Otuoma termed Mr Mututho's statement as "alarmist" and "bordering on rumour-mongering" saying he had no evidence showing that the fish died of the poisoning.

"The levels of chemicals found in the sediments and water samples were not dangerous as to cause sudden death in fish," said the Minister. "Such deaths due to depletion of oxygen are not unique to Lake Naivasha."

Short Time

The scientific explanation given to Parliament is that as long as the phytoplanktons (small plants eaten by fish) die and decompose, the remaining oxygen in the pond is consumed and within a short time, the fish lack the oxygen and die.

A large fish-kill in Naivasha, Mr Otuoma told the House, was because the inflow in the lake had increased suddenly and there was a problem in the mixing of waters. With no oxygen for the plants, they "died" and this further depleted the oxygen making the fish to die. Statements from the National Environment Management Authority indicate that the vast majority of fish, which died, had open mouths (indicating suffocation-lack of oxygen), and that large fish died first, followed by small fish.

The deaths of large fish first, followed by the small fish, was because of a scientific concept about the surface area to volume ratio of the fish's body size.