Do red-eared sliders need anti-ich or water conditioner in their tank?

You have a red eared slider, not a tortoise. A bit of aquarium salt may help, however Nil should be physically examined by your veterinarian or a vet experienced in treating reptiles. Antibiotics may be indicted to treat any infection. Maintain pristine water quality via filtration and regular partial water changes. You can review slider care at the link below. http://www.reptilesmagazine.com/Red-Eared-Slider-Care-Sheet/

The info for red eared slider care can be used for other sliders. Their care is similar enough that it will not make a huge difference. A 10 gallon tank will be sufficient for a juvenile. As Puddle grows, you will need a larger tank. The recommendation is 10 gallons per inch of turtle. A filter is not "necessary", but will greatly help in maintaining water quality. Turtles are quite dirty since they eat, swim and defecate in the water. Frequent water changes, every 2-3 days, will be needed to keep the tank clean. Having a filter will lengthen that time to a partial water change every week or so. Be sure the filter is rated for at least twice the volume of the tank.

An adult slider should have at least 10 gallons of water per inch of shell length. Bigger is always better though, so if budget and space allow then try for a 75 or even 90 gallon tank. Provide a UVB light source unblocked by glass, plexiglass or fine mesh. Heat sources (for the water and for basking out of the water) are also necessary. A basking platform out of the water should be provided. Use a filter that is rated for at least twice the volume of any tank you choose. This will help maintain water quality. You can read more about keeping sliders at the links below. http://www.anapsid.org/reslider.html http://www.reptilesmagazine.com/Red-Eared-Slider-Care-Sheet/

Maintain pristine water quality and proper temperature. You can even bump water and ambient temps about 5 F to aid in recovery. Offer some freeze dried shrimp or krill to stimulate the appetite. Small bits of fresh beef heart may also get him eating. Other protein sources include feeder fish and nightcrawlers.

Reptile water conditioner usually contains chemicals such as Water, Dechloraminating Agents, Synthetic Organic Polymers (Colloids), Chelating Agents, Electrolytes. The reptile conditioner usually also has a chemical that binds calcium in the water as well as a slime protecting agent that is good for amphibians and fish. Aquarium water conditioners (for fresh water fish) contains chemicals such as sulfates such as sodium thiosulfate. Thiosulfate is a Redox reducing agent. Either should be ok for reptiles or fish, however I would stick with reptile conditioner for reptile tanks or mixed (reptile and fish) tanks and for aquaria with fish only I would use specific aquarium water conditioner. The main reason to use a water conditioner is to remove chlorine in water. This, however, can also be attained by leaving the aquarium water fresh from the tap sitting over night. The chlorine will dissipate.

It could be some minor shell rot. Use a soft bristled toothbrush and some diluted betadine or chlorhexidine (Hibiclens) to scrub the affected area once or twice daily. Allow for a 1 hour dry dock (out of the water) after each cleaning. Maintain pristine water quality via filtration and regular partial water changes. If the spots do not resolve or if they spread, have Squirtle physically examined by your veterinarian or a vet experienced in treating reptiles. A UVB light source, calcium powder and multivitamin will promote shell health. You can also float a piece of cuttlebone in the tank for him to munch on as needed. It will provide additional calcium. Find the cuttlebone in the Bird section of the local Petco. The link below will provide additional information regarding the care of sliders. http://www.anapsid.org/reslider.html

I would be concerned about possible fungal infection. If you cannot make it to a vet I would recommend placing them in a dry environment three times a day for 20-30 minutes. You can buy iodine and dilute it a lot and apply small amount to the lesions. Also some pet stores have drops to place in water of tank to help with fungal growth.