It's one of those worst moments when you discover a fish missing from your tank — a rudimentary look revealing the animal in question, board-stiff and dessicated on the floor. Here's what to do...
Caught early enough a fish can recover, even from a surprisingly dry state. However, how you handle the fish immediately on discovery is crucial to its survival.
The first thing to do is get the fish back into some water, but in a safe environment. Simply dropping the fish back in to the tank is a bad idea. It will be vulnerable to the attentions of curious tank mates who will nip and nibble it.
When you pick up the fish it may feel rigid. Do not, under any circumstances, try to bend or otherwise 'loosen it up'. There will be seized, dehydrated muscles inside that will need some time to repair themselves.
Submerge the fish into the tank in your hands and look for a breathing response. If the fish is able to breathe on its own then half the battle is won, but if the gills are barely moving — or worse, dried out and sealed — then the fish needs more help.
If the fish is unable to move, you’ll need to be its gills for a while. Using a tiny pointed tool, such as a pair of tweezers, slightly open the mouth and slightly loosen the gill covers.
Once mouth and gills are open, you’ll need to resuscitate the fish by flushing water over the gills — and there are a few ways of doing this.
Do not hold the fish in front of a powerful flow of water like a powerhead, as this will tear the gills. You require a gentler flow.
Some people like to use a pipette or syringe to gently push water through the mouth. Others like to hold the fish in their hands and slowly move it forward around the tank, like guiding a toy car, copying the 'ram breathing' technique as used in some sharks.
If opting for this method the fish must only be moved forwards. Any backward motion will push water the wrong way across the gills and further damage them.
A fish experiencing any of this will be at the height of stress and the shock of revival can be enough to finish off timid species, or fish already too far gone.
Once the fish is breathing on its own transfer it to a body of tank water in which you have an air pump. A breeding trap will do the job inside the aquarium, but heavy aeration inside the trap will be vital to allow the fish to catch up on ventilation.
Maintain a close watch
If the fish recovers, you’ll need to be on your guard for a few more days.
Despite being through the worst of it, the immune system will be pretty much offline and the fish can easily become a hotbed of diseases. Monitor closely and be prepared to act on any symptoms.