Black Moor - wound

Question
Hey, i have just started a new freshwater aquarium (10 gallon with 4 common goldfish and one black moor). Its been about two weeks since i introduced the fish and i have a few questions. First, the black moor has a very small boil-like wound on the top-right side of his tail (right between the body and the fin). He seems to be swimming normally but not eating much. I was wondering if the other goldfish could affect his eating by intimidating him or anything and what the boil-like wound could be caused by and how can it be reated? I was also interested in feeding habits. Every time i stop by the aquarium or sometimes even when i just pass it the fish go up to the surface looking for food, i feed them 3 times a day (5h apart) and as its been recommended, the amount they can eat in 2-3min. Should i change the feeding habits since they seem to be still hungry every time i pass by them? And final question, i heard people feeding goldfish with lettuce, peas and other vegetables, is that a good idea? and should i grind it first to make sure they can fit it in their mouth (my goldfish are about 2in.).
Thank you very very much!

Answer
Hi Michael
Congrats on your new tank!  Unfortunately, I have some bad news for you.  With goldfish, it's usually recommended to have a minimum of 15 gallons of water for 1 goldie, though some say 10 gallons is fine.  The reason being, some of them like common and comets can get well over 12+ inches long, and they put out a lot of ammonia naturally through their breathing and waste.  With too many goldies in a smaller tank, it will be impossible to keep the water quality good, which will lead to stress, stunting, bacterial/parasitic infections, and eventually death.

Now another thing, to answer one of your questions, it's also not recommended to mix "fancier varieties" with common or comets.  The fancier ones are usually too slow to get the food, commons are quick little buggers :)  So that may be why he's not eating much.  Plus, the ones with the "weird eyes" tend to have a harder time seeing the food.  

For the wound on the fish, that could be a bacterial infection.  Is it on open sore, like an ulcer?  Red anywhere on the fish(hard to tell with a black fish)?  Or is it just a raised lump?

For the feeding, they're notorious beggars, as bad as dogs :)  You need to cut down on the feedings, only once a day, and even skip one or two days during the week, what they'll eat in a few minutes.  And yes, you heard correct to feed them also peas(just split in half so the insides are showing), for lettuce just stay away from iceberg lettuce-it's all water and has no nutritional value to it.  Romaine lettuce, spinach, zucchini, etc. is all good for fish.  I would vary their diet with the veggies, frozen bloodworms, frozen brine shrimp or krill, flake food, pellet food, spriulina flakes, all during the week.  The veggies and spirulina flakes twice a week or so is good to help prevent constipation-which can cause other problems.  Just cut it up to little bite size pieces for them.  

Now back to the tank, being a new tank it's going to have to go through a cycle process.  Basically, fish put out ammonia, and a beneficial bacteria converts that to nitrites, then to nitrates.  Ammonia and nitrites are toxic to fish and can kill them.  The whole process takes about 4-8 weeks to complete.  But as I mentioned, with those fish in that tank, it will never completely cycle, and you'll always have an ammonia and nitrite problem in the tank.  I would recommend bringing back all the commons, and keeping the black moor only in the tank.  You could keep one common and get rid of the black moor and other commons, but they get so big, they really do need a larger tank even for one.  A 12+ inch fish needs much more room then a 10 gallon can provide.  Just my opinion there.  Also, here's a link, need to copy/paste to your browser, that explains in much more detail then I can about cycling a fish tank and problems with ammonia and nitrite poisoning:

http://freshaquarium.about.com/od/startupcycle/Step_5_The_Cycle.htm

Hope that helps, and good luck with your new tank!
Let me know if you have more questions!

Christy