The zoo officials are also apprehensive about the 55 ageing inmates, most of whom have lived longer than their normal life expectancy. Officials said some elephants are over 10 years old and have lived 10 years more than their normal life span. The wildebeest, the tapir, tigers, lions, bear and some ostriches need to be "retired in a condemn cell" so that they may live the rest of their lives in peace without being "stressed" by the visitors.

An official of the zoo said that since the lion pair broke open the eroded cage on March 1, they have found out that many cages needed urgent repairs.

"Feline droplets and urine are highly erosive and the steel cages become eroded so quickly that we need constant monitoring and maintenance," said an official requesting not to be named.

"We roughly need TK 1.68 crore a year for foods, maintenance and other expenses in the zoo but we receive TK 1.15 crore," he said. The zoo authority is now repairing the moats and cages "with whatever resources they have in their hands.

A source in the zoo said that the yearly deficit is running at around Tk 50 lakh. The outstanding bills of the previous year are cleared with the allocation of the current year, and the current year's payments remain outstanding till the coming year, he said.

In a bid to overcome the deficit the zoo authority has recently increased the entrance fee from TK 5 to TK 10. Officials said that the current fiscal's projected earning from the visitors is expected to be around TK 2.75 core. In addition, the zoo is also selling spotted deer each at TK 24,000. The zoo official said last year they had earned TK 12 lakh from sale of spotted deer.

With rapid breeding of hippos, tigers and lions the national zoo is facing an acute accommodation problem. The hippo moat was made for accommodating only a pair but within the last ten years the population has soared to ten, out of which there are six males and four females.

"Whenever a female goes into heat, fierce fights break out among the six bulls. I can tell you, the fights for domination may be spectacular but it leaves behind serious injuries," said a caretaker.

The zoo authority was also concerned about the interbreeding of animals, which they said result in births of animals with physical deformities.

"There is a big demand for exchange programs in the region. For instance, Kathmundu Zoo is asking for a pair of hippos in exchange for some of their surplus animals," continued the Curator of the National Zoo, Mohammad Mafizur Rahman, "we cannot participate simply because we do not have funds for the air freight of the animals."

With 19 lions and 15 Royal Bengal Tigers, the national zoo is in urgent need of launching exchange programs.

The zoo has a collection of 2,220 animals of 184 species.