Hi Jamie
Haven't been on the forums for a while but just popped back on today and noticed your post about pink convicts.
Do you know if these are standard pink convicts or short-bodied pink convicts? You will know by the size of the parents (you say they were from a friend, so they will be able to confirm for you).
If they are standard PCs then, yes, they will grow roughly to the sizes mentioned above. If they are short-bodied PCs then they stay quite small - I have two tanks of them and the largest adult male is about 3inches and the smallest female is just over 1 inch (these are full adult sizes).
Anyway, regardless of their size, you will find that they all need the same care and will behave in very much the same manner - after all, short or long, they are still convicts LOL (in the same way we have tall and short humans)
I've been keeping the short-bodied PCs for about 3 years now so here's a little info for you to bear in mind.
Sexing in pink convicts is quite easy - males are larger and have longer flowing tail fin than the female BUT the most obvious way to tell them apart is that the female will acquire an orangey/reddish flare over her body during spawning (which is usually every couple of weeks in adult PCs!!). So, providing you have a proper mating pair (you will know they are by the way they follow each other around the tank and possibly begin nest building together) keep an eye on them and if you see an orange tummy appear on one, you'll know it's a female. If you notice that the two are NOT getting along (lots of bullying and chasing away) then it could be that they are either not male/female mix but both of same sex OR the male and female have not taken to each other. Sometimes they never do. I guess one just doesn't fancy the other LOL! In the event this happens, you'll have to separate them.
Convicts don't particularly like sharing their tank space with other fish. If the tank is large, you may get away with having other fish in with them, so long as they can mark out enough of their own territory, but even so you'll have to be very attentive and be ready to rescue any fish that are suddenly getting bullied/attacked. The problems usually begin during spawning and get worse once the fry hatch. The parents become super-protective of both eggs and fry and will chase/head-butt/drag and harrass to death any fish that dares move within a foot or two of the nest! (Yes, in the early days I stupidly had my original two PCs in a community tank - big mistake - and costly as I then had to set up other tanks to rehouse the other fish!)
Oh, another thing with convicts is that they like to rearrange your tank a bit. If you have real plants in there, be prepared for them being moved and shredded. It has cost me a fortune in wrecked plants so now I only use silk plants in their tank. They also move gravel and will dig a large hole down to the base of the tank with a barricade of gravel up around it. That's usually where they lay their eggs or some other flat surface.
They like hidey holes, so pots/caves of some sort are a good thing in the tank (they sometimes lay their eggs inside tank ornaments/caves).
Foodwise, they can be fed on a variety of things but if you can get hold of live foods such as brine shrimp/daphnia/bloodworm etc this is good at least once a week - or frozen is just as good. For their daily feeding you can give them a good quality tropical fish flake/crisp food or the sachets of jellied foods, occasional boiled and shelled peas (just squash a couple and add to tank), pellets, algae wafers etc.
One thing to bear in mind is that they do mate very regularly and it's quite common for them to eat the fry within the first week or two. This used to horrify me at first but I came to realise that if every fry survived I would have a huge problem on my hands of rehoming them and unfortunately there just aren't enough people out there that want PCs.
Hope you enjoy your convicts - they are great little characters and a lot of fun to watch. A mated pair can be quite comical to watch!
Regards - Athena