In my 20 gallon I have 3 zebra danios, 1 bala shark, 1 rainbow shark, 1 rosy barb, and 1 plecostemus. They are all at their max. size, and have pretty good dispostions. None of them are upset easily. Would it be alright to add a spiny eel, or would that cause problems with my community? (I have already calculated volume, so that is not an issue).

thanks,

laurita

Ur plec is the common plec right? (Not the Zebra Plec or one of the miniature varieties rite?). Common plecos ate full size at about 15-18inches!!! Is yours REALLY full sized? I've got 3 plecs in my pond... at that sort of size.
That's my biggest problem with ur set up.

Next your bala shark.... err, this fella may be peaceful, but it also gets to about a foot!

Spiny eel.... It would be good if you checked the diet of these eels. They'd probably have ur danios for lunch and barb for dinner as it gets bigger.

For a 20gal tank.... u're WAY over the limit, with too many tank busters. For ur pleco, bala shark and spiny eel.... a 100gal would be more like it.

Okay...whoa. I guess I didn't make myself very clear. When I say max. size, I mean I don't think they will grow anymore. None of my Fish are over 3 inches, and I've had them for over 2 years. The guy I got them from ran out of time to care for them, so I adopted all but the rainbow and pleco. He had them for quite awhile before I got them, and though I know it's a myth that all fish grow to the size of their tank, I think it is possible some do. If the Spiny eel does get too large, I intend to sell it or trade it in. But I would like to try one for at least awhile. Alright, now that everyone knows the real facts, does the advice change?

Laurita

fish actually can be stunted in their growth based on the size of the tank.........this is unheathy for them and stresses them out. The only other comment that I am going to make is that Bala Sharks like to be in a group of atleast 2, preferably 3. They also like to swim alot and IMHO should not be in a tank smaller than 125 gallon assuming that you have 2 or three of them. The reason for this is that Bala's can and most will get up to 14 inches in size.

oops, forgot one thing.......Bala's tend to be slow growers

... they only grow slowly if they're restricted and conditions aren't right. In South East Asia, the bala shark is a table food fish.... so it HAS to grow pretty quick to be viable.