In the heat and humidity of the Glasshouses, the tropical plants grow very fast so there is rapid build up of detritus in the water, especially once the roots of submerged plants thicken and break through the pot walls.
Alan Langley, Acting Glasshouse Supervisor explains:
'It's a job we do probably every other year. We start by partially draining the pool and then scooping out the fish, mostly goldfish and some tench, into large black bins that will be their temporary home until the end of the week. We'll then clear out all the debris, prune back, re-pot and re-label the plants, and pressure wash the walls of the pool. We'll then refill with fresh water before releasing the fish back into the pool.'
It is commonly thought that fish have very short memories, but Alan is not so sure:
'I'm convinced the older fish remember the last clean out as they are so difficult to catch. There's a Garden Cafe brownie on offer to the horticultural trainee who succeeds in catching Cyril, the large black tench that skulks about the floor of the pool, and another brownie for the elusive fan-tail that has so far avoided capture!'
The fish pool is currently closed to visitors while this essential maintenance is carried out. The Tropical Rainforests display will fully re-open by this weekend.