Identify fish and bullying

Question
Ok...I will try to ask this question without aggravating you too much. I work at the front desk of a hotel and we recently had to take over the care of two fish from the restaurant we own because the lease holders just left them. We have a small like ten gallon (I guess) tank in lobby with one small black shark-looking fish with a orange tail. Well the two fish we "adopted" are very large goldfish-looking. They are oval shaped with a triangle type fan-shaped tail with slightly bulging eyes like a goldfish. They are solid orange in color with a small heart shaped mouth. I cannot figure out what type it is. But my main problem is that since we have gotten the fish, they have changed they're colors. One is lighter orange now and a bit smaller and the other is still same size but has lighter white "patches' on it. Im thinking that is some sort of stress factor and according to your "break-in period" article they may adjust after awhile. My other problem is the larger fish is a bully. He/she will not allow the smaller fish to eat. He/she constantly swims full-steam into the other in a head butting motion. The other does not fight back and sometimes even floats on its side "playing possum". The smaller fish also hides in the corner of the tank behind a tall plant, I believe, to escape the bigger fish. I have tried to seperate them when feeding but as soon as I put them back together he beats up on the smaller fish again. I didnt really notice when they were first brought over to the hotel but I believe they were at one time the same size and have always been in the same tank at the restaurant. We have the larger tank here at the hotel now, but the previous owners did not take care of it so we will have to repair/replace alot to get it back into working condition. Sorry for the long and drawn-out question. Is there anything I can do maintain and raise these fish in a health manner? Thanks again, Melissa in NC

Answer
Hi Melissa;

They are probably fancy goldfish. They are very messy fish so they really need a lot more space than a little ten gallon. To help them feel better until some decisions can be made, replace 25% of the water every day for the next 4 days. Fresh water helps the fishes' immunity and should help the energy level of the lethargic fish. After the four days of changes, change 25% every 3 days.

Each goldfish needs at least ten gallons just by itself. They get to be 6 to 8 inches in body length without even including the tail. (yikes!) The bullying may still continue in a bigger tank though. Some goldfish are just jerks that way. :-/ What I would do is get a 20 gallon tank with a good power filter and no heater. Move the smaller goldfish over to it once everything is set up and running with room temperature water and a good water conditioner. The more aggressive goldfish will be just fine with the shark for a few weeks as long as you don't see them fighting and there are no missing fins or injuries on either one. Make a 25% water change at least twice a week in the little tank though. The new tank needs 6 to 8 weeks to break in. Once that's done, you could try adding the bigger fish to it with the smaller guy. If he starts up with his nasty shenanigans again, take him out and leave him a single anti-social guy to his own ten gallon apartment. He will probably do the same to other fish too.

Goldfish are coldwater fish so being in a tropical tank with a redtailed shark is not good for them. They need their water to be no higher than 72 degrees. The shark needs it to be 76 to 80. The shark will also get aggressive and nippy. They are terretorial and will kill others to get them out of there eventually if the tank is too small. He should be alone in the ten gallon. A bigger tropical tank for him with other community tropicals would be okay, just not in the ten. Here is more about them and their habits;

http://www.fishprofiles.com/files/profiles/264.htm

Here is more about the care of goldfish;

http://www.firsttankguide.net/goldfish.php

Don't worry about aggravating me. It takes a lot to do that, trust me! I am a stay-at-home-mom of four kids, the two youngest being 13 year old twin girls. My boys are 18 and 23 so I've had my share of challenges over the years. So, as long as you don't use up the gas in my car, ask me to wash and dry your clothes at 11pm, leave dirty dishes all over my house or invite friends overnight without asking....I won't get aggravated with you.  ;-)

At Your Service;
Chris Robbins