Alan, the tank their in probably isnt ideal but its all that was empty.
Theyre in roughly 30x18cm tank, with about 12cm depth of water.
Temp is around 27-28 degrees.
Dont have a sponge filter spare atm, so they have just an air stone and i've been doing small water changes. Top is sealed with a plastic wrap cover.
Theyre definately in there (or something is anyway), they just dont seem to be growing