How To Take Care Of Your Doctor Fish We strongly recommend you to fully understand how to take good care of Garra Rufa doctor fish before you proceed to purchase them. To build a happy and comfortable environment for your doctor fish, here's a few things you need. Water Filter (Internal or External) that is suitable for your size of tank. The water filter show comes with compartment that allows you to fill in filtration media like ammonia stone, filtration sponge and etc. Kindly consult your local aquarium for suitable water filter with right filtration media to maintain a fish tank.