Yellow Belly Slider and Red Ear Slider together

Question
Hi we saved a YBS from a river damn that was being torn down and we've had him for about a month now. He is a about a inch and a half max. And then we got a RES about a week ago and he is maybe a inch in width max. We have them in a 15 gallon tank for now bc we just dont have the money to buy a bigger tank right now. When we got the YBS i bought the starter kit that came with a filter, rock, and heat lamp idk the brands. The eaters stays about 75 cool areas and about 80-90 basking area. We have city water. I bought rocks for the bottom of the tank and baby turtle pellets to feed him. He didn't eat for a couple days and would just lay on the basking rock and sleep and then at night he started eating a couple pellets and then was fine eating during the morning and afternoon when i would feed him he would eat all of them. His shell wasnt soft at the bottom at all above his tail. Well when the RES came we were very cautious due to the fact of the YBS being slightly bigger and i heard they could eat each other. They were fine, they even ate together during the feeding time which was a big concern. We also fed them crickets and little bugs, moths, etc. and they were eating. Well a couple days ago i noticed the YBS not eating but his behavior hasn't really changed. We just cleaned the tank and we always check their shells when we do and the RES shell is fine and his was soft when we got him, now the YBS shell is soft at the bottom above the tail and a little more around the edges going up, what does this mean? Is he sick or just growing? Neither one id acting aggressive towards each other. What should we do? I don't want him to die :(

Answer
Hi Jazee,

I'm afraid if you want to keep turtles you are going to have to be willing to spend some money for proper setup, because otherwise maintaining the health of the turtles will be difficult.  A 15 gallon tank is simply too small, even for one small hatchling.  For two, you really should have about a 30 gallon tank, keeping in mind that sliders grow fairly quickly and they will need bigger accommodations as they grow.  As adults, two sliders really need about a 200 gallon tank.  The filter should be able to handle twice the tank's capacity (so a 30 gallon tank needs a 60 gallon filter), and three times if the tank is on the small side.  If tank size and water quality is inadequate, the turtles will often develop nagging skin and shell infections that can be difficult to treat.  The other issue with overcrowding is that territorial problems can develop as the turtles mature, and then you can get bite wounds, etc.  So proper housing is very important.

Those starter kits are pretty useless.  The basking light may be OK, but it doesn't sound like you have a source of UVB (not UV or UVA, but UVB, which is a special reptile bulb).  Without adequate UVB, they can't metabolize calcium properly, and that may be the problem with the YBS' shell.  I would get a ZooMed Powersun (100 watt) bulb, which provides both heat and UVB in one bulb.  There may be other UVB bulbs that are cheaper, but most are unreliable.  The Reptisun 10.0 (tube bulb) is also good, but I think the Powersun is easier to deal with in terms of optimum height.  

A good variety of food is important.  Pellets are good, along with other sources of protein, and they should be offered fresh greens as well.  I'll provide some links below that will give you more food ideas.  If you have other questions, please post back!

http://www.redearslider.com/
http://www.austinsturtlepage.com/Care/caresheet-red_ear_slider.htm
http://www.austinsturtlepage.com/Care/care.htm
http://www.austinsturtlepage.com/Care/waterquality.htm
http://www.austinsturtlepage.com/Care/housing.htm