Ranchi: The multi-crore fish aquarium at Bhagwan Birsa Biological Park at Ormanjhi here is battling power woes since Wednesday evening, when its 100kva transformer burnt after massive thunderstorm and lightning, putting 1,500 exotic fish of 250 varieties under severe threat.

To keep them alive, the zoo has deployed a generator to run the massive aquarium - with 58 compartments that have species such as red-bellied piranha and alligator gar - but it is getting tougher with every passing hour.

A zoo official explained that continuous power supply was essential for the survival of a fish in an aquarium.

"Without power, the fish can't get oxygenated water that they need to live," he explained. "We have no choice but to run the huge facility on a generator. But, that is okay for few hours or a day at the most. Running the facility on a generator for days is not feasible financially and operationally."

He added that they had been calling up electricity officials every day to request a replacement of the transformer but to no avail.

The zoo has two transformers, one exclusive for the fish park and administrative wing and another for the main zoo arena on the opposite side of Ranchi-Ramgarh NH33.

Zoo director S.K. Gupta conceded they were all worried about when the transformer catering to the fish aquarium would be replaced.

"Power board officials here in Ormanjhi have not understood the urgency of replacing our transformer. Someone said their priority is first to look after the residential areas. But, without power, the fish would die," Gupta said.

Assistant electrical engineer of Ormanjhi circle, Lalji Prasad said his area was worst hit during Wednesday's thunderstorm due to which at least eight transformers got burnt and overhead poles and cables snapped as trees or branches fell.

"We are running against time and it will take at least one week to restore smooth power supply in Ormanjhi if another round of thunderstorm and wind doesn't happen. As far as the zoo is concerned, it is on our priority list," Prasad said, promising transformer installation by "tonight".

"By tomorrow (Sunday), the zoo facility (fish aquarium) will get proper power," he promised.

Launched by chief minister Raghubar Das last year and currently among the star attractions, the aquarium built at a cost of Rs 3.6 crore is the first-of-its-kind facility in any zoo in the state.