you mean a Bubble Tip Anemone? Well, that all depends on your tank first. How long has the tank been set-up and what kind of lighting are you running? We need to figure out if your tank can even maintain and keep alive an anemone before we think about compatability issues.
i've had the bta in a tank thats been set up for 2 years and have had the BTA for over a year its going great it's huge running 65w pc on a 20 would be moving to a 110w pc on a 75
the new tank would be a whole new set up, but have most of the water form my 20 and also some live sand from another tank im breaking down witch iv'e had for 3 months.
I think Bta's are easy to keep iv'e never had any problems wioth the ones i own iand i have 4 of them the one ill be moving is the biggest but also the one i've had the shorest.
so i know i can keep them, its just a matter of will the puffer nip at it as well as a niger trigger witch i plan to get much later,
dont want to tax the system to much need to let it age.
and the other main consern would be the eel slithering by it and getting stung.
I would not worry about the niger, the puffer may nip in the beginning, but you more have to worry about polyp-y type corals, like zoos, gsp and the like - I doubt a large bta will be much to it's liking.
It is definitely worth trying, the biggest challenge, imo, will be water quality - puffers do a number on that! good luck though.
don't worry about the eel getting stung, btw. They are a tough critter and the sting of a BTA is really weak compared to just about any other anemone. I bet even glass anemones have a more potent sting, would you worry about your eel slithering on aptasia? nope, me either!
well i wont have to worry about him eating corals, I already have 3 BTAs in my 75 and dont have the room for another one, this one is the size of a foot ball it took up all the room in my twenty. If i put the tomato clown in there with the puffer you think he'll defend his home. Hes a big guy to.
tomato clowns have a pretty stalwart attitude, and should be fine. Of course eels often decide to surprise me no matter what I think I have prepared for - tricksy devils they are... I'm assuming that your eel is a snowflake or something similar - any of the Gymnothorax genus will more than likely love the taste of tomatoes... pun intended.