Is stunted growth reversible?

Question
Hello, I've adopted 4 turtles from 3 diff. sources.  One pair is a male/female both about 4 yrs. old and both have shells about 4 1/2 to 5" in length.

I also have a male who is 10-11 yrs. old with a shell length of 6".

Lastly a 3 yr. old turtle with a 3" shell (male).

All are healthy, eating great.  All came from tanks which ranged from 10 gallons to 20 gallon tanks.  Right now I have the  4" male & 3" male in a 75 gallon tank.  They have an above tank basking area so it allows total swimming room. So far they've been getting on fine.

I have the 4 yr. old (4" female) in with the 10 yr. old male (6") together in another 75 gallon tank with same conditions as above.  I may end up putting the female by herself because she seems to nip at the male she came in with & this older male too.

After all of this explanation, I realize these turtles are probably stunted in growth.  I don't really care if they get huge, I actually would rather they stayed the size they are or a little bigger is fine because with a home sanctuary going here for small animals, two 75 gallon tanks are all we can afford.  Remember, these turtles came from far from ideal conditions and nobody else really wanted them, so I feel we're doing them a big favour.  I do regular water changes, probably more than usual & they're not huge turtles.  There is ample cannister filtration on each tank as well.

Thanks for any help!
Paula

Answer
Paula, These guys were far from being in ideal conditions. The turtle as hatchling's should have been in at least a 20 gallon tank and for less than a year. The will be sexually mature by 2 to 5 years for males and 5 to 7 for females. By then they should be at least 6 to 10 inches. These are not small turtles and by sexual maturity I would not keep them in less than a 125 gallon tank two in each if they do reach full potential. You may be able to get them caught up abit depending on the size of your tank and feeding habits which I am assuming were not that good. They may never reach full potential but your tanks are good for the size they are now. Remember by full size these guys are about 12 inches or abit more and almost the size of a small dinner plate. The filtration you have is excellent. The size of the tank is a problem but, it will be ok temporarily. She is probably nipping because she is acclimating to the new tank  or they are not getting enough to eat or she simply doesn't like him they have alot of personality. I am going to give you some tricks that will help: 1- feed them in a separate container. You can use a small plastic tub but, make sure the water is deep enough for them to swallow water when they eat their tongue is fixed and they don't make alot of saliva. They usually go to  the bathroom soon after eating.......rinse them and return them home. 2- make sure they have a nice size basking area around 80 degrees and the ambient temp and water about 75. The heat helps them digest their food and raise their body temperature. Since I am sure you know they are cold blooded. 3- These are not big meat eaters though need small amounts to keep their protein up. What I do is take some blanched spinach or kelp or romaine and layer the food. I add carrots grated, white tuna, always pellets as a supplement, they tend to love dandelion greens, bok choy, lean chicken boiled. With the fruit try and see what they like. It is so much easier to freeze it and cut it into squares as soon as you know how much they eat. Adding calcium powder I would also recommend. these guys kept in good conditions can live up to thirty yrs. They should be full grown by 10 to 15 yrs. Thank you for saving these wonderful creatures. If you have any other questions please just ask....Good Luck, Tina