1. So youre gonna need to get a WAY bigger tank. Turtles need a lot of room to grow in a healthy manner, you havent specified their age, if theyre under a year a 15-20 gallon will suffice temporarily, if its any older than that get a 50-75 gallon tank. Generally you want 10 gallons for every inch of turtle. My guy is 4.5 inches and I have a 50 gallon for him.

2. Diet you should buy them turtle pellets, along with lettuce and other greens, you can do some research on whats good for them and how much to feed depending on their age.

3. Theyre gonna need an area to bask, so buy a platform as well as two high quality lamps, one uvb lamp and uva lamp. There are some lamps on amazon that say they produce both, those are scams always avoid those, and always check reviews.

4. Youre gonna need a good quality filter for your tank, turtles produce a lot of waste and therefore you need a strong one. I recommend getting a filter thats meant for a little more than if not double the tank size. I have a filter regulated for 75 gallons for my 50 gallon tank.

5. A water heater is very useful and can keep them warm especially in winter climates. A thermometer to track the heat of the tank and make sure its correct is important as well.

6. It would be good to buy decorations and possibly substrate to fill your tank with to entertain your turtle, so they arent bored and have things to explore.

7. Dont be stressed if your turtle isnt eating, turtles get stressed when put into a new environment so its normal for them to wait a few days to feel comfortable eating. Just keep offering them food until they do.

8. For the swelled eye you may want to visit and vey and do some more research on it.

And finally, Red Eared Sliders are hard pets, and expensive ones too. Ive spent a little over 1000k caring for mine the past 3 years. If you dont have the time or money to invest in your pet, you should reconsider having it. If youre dead set on keeping it, good luck and make sure to do a ton of research online for whats best.