For the tank size, you can use a 20-gallon to 40-gallon tank. You can feed it live, frozen, and flake food.
For the tank, you can follow these tips.

1. Use a vacuum cleaner and gravel
2. Replace 10 to 25% of the water tank with fresh water.
3. Rinse the filter with the removed tank water and replace the filter media.
4. Check pH, ammonia, and nitrite levels.
5. Add lighting and substrate

Hope it's useful😁