How can I catch fish that cannot be caught with a net?
How can I best (of course considering the requirements of the fish) catch Lake Malawi cichlids in an aquarium (there are many juveniles that must be removed from the tank)?
it is in many cases sufficient to use two nets: Use one net (usually the smaller one) for chasing the fish into the calmly held second net. This is rather successful after some practice, and causes little stress for both the fish and the aquarist.
If that does not function you can try and use a plastic fish catcher (it is shaped like an oversized tobacco pipe). These units are nowadays not very common anymore, but provide useful help. They are transparent, the fish can therefore not see them. Pressure variations when handling it are of course still noticed by the lateral line organ, nevertheless it is often successful when catching fish that are almost impossible to catch with a net. Nowadays, these fish catchers are manufactured from unbreakable plastic. They are a good choice especially for fish that easily entangle themselves in a net (some catfish!).
Finally there are fish traps that are dimensioned in a way that adult fish cannot enter. You can, for example, use a plastic bottle of which you cut off the upper part and put it back in in reverse position (like a funnel). Important: Such traps need to be checked permanently! They can otherwise literally become death traps for air breathing fish (labyrinth fish, Corydoras catfish etc.)!
Dr. Bodo Schnell