at what age and what size should i move the fry into a seperate tank away from the parents
Opinion on that varies and there's no real "right" time to remove them. I've allways left them with the parents as long as possible (weeks-months) and that mostly seems to work ok for me (allthough there is some risk the fry may be eaten if the parents wish to spawn again). Others remove the fry as soon as they are free swimming and that can work well too. It's really a personal choice and when dealing with convicts you will find for yourself what works best over a series of spawnings. If you wish to experiment a little to find the best plan for the second batch of fry, you can remove half the first batch early and leave half with the parents to see which grow and survive the best.
To remove the fry, the easiest way is to suck them from the tank via a syphon or gravel vacume as the parents are very defensive and netting them can prove difficult.
Many inexperienced pairs will eat their own fry or eggs during the first attempts at spawning. Don't be alarmed too much by that as they will generally allways get it right after a couple of attempts. Some will also be perfect parents from day one though. You can be fairly confident that there will be many many more where the babies came from whatever happens though, so keep that in mind. Established pairs can breed as often as every 2-3 weeks after a hatch and there is generally at least 100+ fry in every brood.
does that tank have to be heated?
Yeah, they need the same water specs as the adults.
is there a certain size tank that i should put the fry in or will any old tank do?
Needed tank size is going to increase as they grow. The minimum your going to need within a couple of months is around 20-30gal (however that wont be adequate in late adolecence or adulthood). Keep in mind that many of them will likely reach the same size as their parents and will have the same requirments. You will need a plan to unload them somehow as your unlikely to be able to house that many fish as adults. They will also inbreed amounst their own siblings (that should be avoided if possible) and will interbreed with their parents once adults. At 100+ fish per spawning from multiple family pairs, it's within reason that you could end up with constantly thousands of offspring being produced months down the track, which can become a big dilema if you can't house them, feed them and no fish stores will accept them. It's not a bad idea to have both a good plan for the fry and also some way of splitting whatever convicts you are keeping into single sex tanks to avoid offspring should the need become dire.
Hope those points help a bit

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(p.s ... your fems look mature enough and are showing good colour so I don't think you'll be waiting too long

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