I'd say your best bet would be to herd them into a glass rather than net scoop them (that's if you can get your hand in there with mom and/or dad).
As far as temp goes, I'd assume 78f would be best. I don't know if this is true with convict fry, but some smaller cichlids have metabolism issues that effect their growth rate if the temp is too high.
just what i have noticed with mine (they are about .25") that they are EXTEREMLY curious... is, i put the net in there, and they all go swimming towards it to figure out what it is, and i can catch quite a few at a time.