Aquarists assist with koi relocation at Mitchell Park Zoo
When I received a request from the curator of Mitchell Park Zoo for assistance in moving their koi fish from a large pond to a holding tank in an adjacent enclosure, I was confident we would be able to assist. The uShaka Sea World collections team are experts in the fine art of fish relocation, where minimal stress is paramount to the well-being of the fish.
We headed off to the zoo to assess what equipment and manpower would be required to remove 115 large koi (some up to half a metre long) from their pond to facilitate cleaning the exhibit. The plan was to return the fish back to the pond once the exhibit had been cleaned.
Excited at the prospect of being able to assist the Mitchell Park Zoo staff, and confident that the Sea World team could add value to the exercise, we set aside a whole day to assist with the big move.
Monday 29 June was allocated for the move and optimistic uShaka staff members arrived at Mitchell Park Zoo early and eager to start the day. The pond where the animals are housed is waist-deep when full with a thick layer of sediment on the bottom which, when stirred, reduced the visibility to almost zero. This made it extremely challenging to locate and gather the fish in their approximately 20 000-litre home.
To combat this challenge the team used specially designed barrier nets to corral the fish. Adopting a slow, cautious approach, the fish were caught and transferred to their temporary quarters using nets with rubber mesh to prevent potential damage that could have been caused by handling the fish.
An oxygen cylinder was set up with a regulator and airline running a ceramic air diffuser into the temporary holding tank as an extra precautionary measure to reduce stress. In addition, we added a dose of Fish Protector – a product that soothes "bruises" and adds a thick slime coat to the fish to protect them from possible infections.
As with all fish moves, we spent many hours planning the exercise to ensure minimal time was spent executing the move. The initial phase of the staged exercise took just less than two hours.
Once the fish were out, Mitchell Park staff worked side by side with Sea World staff to clean the exhibit, which included scooping out several hundred kilograms of sludge. Then it was time for trimming and tidying the plants, and cleaning the walls, rocks and bottom of the pond. This took most of the day and by late afternoon the pond was ready to be filled and fish reintroduced.
Being such a large pond it took two days to refill, and on 1 July I went back with a few colleagues to help the zoo staff transfer the koi back into their sparkling “new-look” pond.
It felt great to have been able to assist Mitchell Park Zoo. Next time you visit the zoo, in the heart of Morningside, Durban, include a stroll past the koi exhibit, where you can sit for a while, relax and marvel at these majestic freshwater inhabitants.
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