why not use a cheap filter pad? they come in wide thin strips, which is ideal.
i dont use that kind of thing because i have my babies (guppies) in a breeder box til they are ready for the main tank. when the babies get a bit cramped in the box i divide the batch or use a load as feeders for the oscars x
what colour fancy guppy? i have just had a batch each of flame-tail and neon blue fancy guppy fry mature into their colours, some are well pretty. and there is a random anomoly colour male fry from the flame-tail that i have no idea what it would class as :L
and how many have u got? i love little babies!! xxx