Corydoras Not Grown

[Shell_bell]

Hey everyone I'm new to this forum and just wondered if anyone had any ideas.

I've been keeping fish for a number of years and my all time favourite's are the corydoras! I had a shoul of 10 in a 65 gallon tank along with a few other fish and decided to get some more I bought 6 about a year ago (albino, same as the original) they were tiny when I bought them but even now they're still only just under an inch including the tail! They all appear healthy and active just wondered why they're all still so ickle!! As far as I can remember my original cory's grew fairly quick

 

[Tizer]

possible stunting prior to you buying them.

 

[Inchworm]

What can happen while they're fry is that they didn't get the very frequent water changes they need at that point in their development. Each cory produces a small amount of a growth hormone. In their natural environment, it's no problem because there is more than enough water to dilute it to where it can do no harm to their brothers & sisters. When natural over population occurs, the young population is reduced due to the amount of hormones in the water. However, in a small space, this could get concentrated to the point that it causes the adverse effect of stunting.

The fish might be very healthy in all ways but for their size. Unfortunately, this is not that unusual.