Hello all in need help. I have a 400 gallon aquarium with a horn shark. My sestup consist of a 400g tank , 60 gallon sump. filter socks, and a skimmer. I would like to get a eel and and a stingray. Is that possible with my current setup and is theirr anything i can add or do better to make it optimal for them. I feed silverslides is there anything else i should be doing