Two of my harlequin rasboras got into the compartment for the trickle filter. There's not enough room to maneuver a net in there (particularly seeing as my boyfriend wasn't home to lift off the hood for me) so I made this contraption to catch the buggers.
Needs:
Wool
Some kind of pot
A stocking leg
Slide the 'pot' down the leg of a stocking until reaching the top. Alternatively (like I did), if you don't have the toe, simply knot off the bottom like so:

You should have some slack on the other end of the tub, like so:

Loop a length of wool around the 'slack':

Stretch the slack back on itself, over the edges of the pot like so:

You're almost done. Now put your fingers into the hole and stretch it back out, making it as large as possible. It should now look like this:

Now, sit and wait for the fish to come in between the glass and your contraption and then lunge. :P Even if the fish is inbetween the stocking and the glass it should manage to find itself into the hole you've created. Once there, pull the two strings in unison. The hole will cover like this:

You've caught the fish. :D
No, this is probably not easier to use than a net - but in a tight space it is handy. I'm so proud that it actually worked and my two harlequins were back with their school quite quickly.
This is also good for fish that jump because it seals them in.