Do you have a Bristlenose Plec by any chance in the tank? The babies look like young BN's. How BN's breed is the female will lay eggs and then the male will take them and incubate them. He then chucks em out of his pit when he has had enough of them. Usually at a similar size to what you have posted photo's of.
Well, if the two catfish are the same, then they could be a breeding pair. That could explain where the babies are coming from. However, all catfish are not the same. There are many different catfish. There are large catfish like the common pleco, smaller plecos like the bristlenose previously, mentioned, pitbull plecos which only grow to an inch or two. Then there are corydoras catfish, pictus catfish, the list goes on and on. Are your two actually the same? (I guess they must be since they apparently have bred! )
I'd still look into a rearing tank to put the juvies into. Juvenile fish need a lot of room to grow out in. They will need a large number of water changes on a daily or nearly daily basis. (Fish put out a hormone to inhibit growth, water changes will allow the fish to grow out to proper size.) You are going to want to find someone who will take the fish when they grow up a bit more, or find someone who will take them now. Hopefully you will be able to get some money or store credit for them.
No they don't look anything like each other I do have a huge tank it's 6 by 2 ft is that big enough?
There are 6 now, will there b more? I've never had fish breed in my tank b4 we've had it 5 yrs now!