If you look closely at the top picture, if you look at his tail, there is a light patch, that is now BLACK. What do I do ? the black colour is increasing, and it's not colouration because when i got my fish home and put him in the tank the black on his sides came off, taking his scales with it.

Ammonia burns and poisoning. This isn't the "tank" you usually keep the fish in, right??!
I think I see some patches of missing scales as well? These can easily get infected if you'll keep him in this jar any longer :/
You'll need to buy him a 20 gallon tank if you want him to heal up and grow big and strong I suggest you go look for some second hand tank if you can't afford a completely new one.

HI, Great advice from Goldie and Nossie... also you havn't given a lot of details about your fishes current environment, it would help them further understand your problem (see sticky in health and illness)... Sorry to say it but if you dont do something now for that fish it will more than likely soon meet its demise... I hope it doesnt live full time in that bowl, if so it may be dying of boredom as well... I apoligise if the tone of my message sounds harsh but animal welfare issues are close to my heart...  Cheers > Ron

Thanks Goldie, but I feel I was a little self righteous and harsh... and you are right, we are passionate about fish and animals, and its not just the bowl thing with fish, I am also not that happy about giving animals/fish as prizes (or gifts) which really isnt iluvmygoldfish' fault... I hope your advice has helped them and the little goldie gets better soon... Cheers all> Ron

Ron - Yes, I agree...my very very first feeder goldfish died after a week when I was, like 7 years old because I didn't know a thing about fish! I never even took it out of it's little plastic container but fed it several peas every day until the water was very murky...I don't know how it lived that long. I never should have been given it. We all have room for improvement, I suppose.  I also think giving fish as prizes to Oscars and other large fish is sad as well... but that's just my little opinion.

Iluvmygoldfish - good to hear that you are going to spoil your friend.  Now you said 10/20 liter tank? That's a bit different from 10/20 gallon tanks...(pauses to do math) you should get your fish a roughly 28/55 liter tank or a 10/20 gallon tank. Maybe you meant gallons, sorry.  But a 10/20 liter tank would be much too tiny.

You should also read up several helpful articles you can find under the general discussion part of the website. They will help you to understand better the importance of having all these things for your pet. 

Goldiegirl i think a 10 gallon tank is 40 liters and a 20 gallon tank is 80 liters.

iluvmygoldfish you need to get a 10 gallon tank which is 40 liters. A liter is smaller than a gallon so 4 liters go in a gallon.

Forgive my mathmatical errors...should have double checked.  That's right because a 20 liters is 5.283 gallons roughly, which is much to small for a goldie. Sorry everybody!  And thanks Ron. I'm not sure about that, not having been to a carnival in a while, but I do know in California they're trying to pass a law forbidding all pet stores from selling goldfish at all...idk if that's gonna happen or not. While I hate that so many goldfish end up in homes that end up having the goldfish die simply from ignorance, I would be sad if I couldn't walk into a store and buy a goldie at all...

I agree. NOT instructions that say, "one goldfish will do quite nicely in a 5 gallon tank...a 10 gallon tank will easily house 10 goldfish that are each 1 inch long..." 

Karma to that Ron, karma to that.

Goldiegirl: People live in the misconception that goldfish should die after a few weeks or so, they have no idea how old they could get or how hardy they are! Imagine how much abuse a goldfish can take before it dies if it can live for months, even years in a bowl?!

Our oldest goldie so  far is 7 years, he's gotten a little tumor on his eye and turned blind in one eye though :'/
Hope to see mine live for at least 20!!!

Yeah, I don't think it would be very complicated to remove it, but I don't have any practice, nor gear to perform the procedure :/
Especially since it's so close to the eye, I wouldn't want to cut wrong or anything!

But, lazer beam? For fish? That's a cool invention.. xD Nice to know that it works too, considering that popeye tends to be a pretty nasty disease to treat.