Goldfish lying sideways at bottom of tank

Question
My goldfish lies sideways on the bottom of the tank for long
periods of time, but is still able to swim properly when he wants.
He has very recently developed a kink in his tail and some black
marks around the tips of his fins. When I first noticed any
problem he was upside down and pretty much unable to control
himself and I was sure he was going to die, but then I changed
his water (his babysitter allowed his water to get a bit dirty) and
he came good within a few hours which lasted for a day and now
he seems to be taking a turn for the worst again. (although not
yet as bad as he was). I Don't know what the pH or anything is
(probably should find out?), but I have been using water
conditioner and I don't think he's been electrocuted or subjected
to anything too shocking like temperature changes ect. He's with
another fish (a black moore I think) who seems to be just fine.
What do you make of this?

Answer
Hi Matthew;

It sounds like he may have a swim bladder problem along with a digestive disorder. The swim bladder is an organ inside the fish that fills with blood gasses when the fish wants to swim up in the water. It is right below the spine so it keeps the fish upright too. If it fails it deflates and can't hold blood gasses. This means the fish sits on the bottom. When the fish floats upside down it could be a digestive problem causing gas in his belly. Since it seems he isn't unbalanced all the time and there is black on the edges of his fins I would suspect a water quality problem. Black on the fins like that is often from ammonia burns.

How often does the water in the tank get changed? All aquariums need at least a 25% change every week if the tank has a filter. If there is no filter it needs a 100% change at least every week. Goldfish must have a filter in their tank to thrive. Vacuum the gravel every 2 to 4 weeks.

How big is the tank? Goldfish need 10 gallons per fish to do well. They are messy fish that get to 6 to 8 inches long and just need a lot of space. High ammonia and nitrite levels will be the result and slowly poison the fish on a continuous basis. They become chronically ill and eventually die from it. Some sooner, some later and not every fish is affected the same way.  

How often are the fish fed and how long does it take for them to eat all the food given? Overfed fish will often develop digestive problems that can also affect the swim bladder. The digestive system and swim bladder are connected in goldfish. If your fish are fed twice a day, they should finish all the food within 2 to 3 minutes. If they are fed once a day, they should finish it within 5 minutes. "Finish" means that there should no food left anywhere in the tank after 5 minutes. Look on the gravel and decorations. The fish will nibble around for awhile looking for extra food after that time but if you actually see any you are overfeeding them. Even if they do eventually eat it all they don't digest it properly and the excess waste just pollutes the tank. We all overfeed from time to time. We just have to change our ways once we realize we've done it.

What kind of food do you feed? Goldfish do okay on a flake or pellet diet but they need more than just that to keep their digestive system working well. Feed cooked green peas (with round skin peeled off), shredded carrots, green beans, raw romaine lettuce, raw slices of squash and cucumber. These foods are given in addition to the basic diet and don't rot like the basic dried diets do. This means it is okay for them to be in the tank for up to 12 hours while the fish nibble them all day.

What kind and size filter is on the tank? Goldfish need good filtration because they are pretty messy fish. Power filters or canister filters work best for the amount and type of waste goldfish produce. Undergravel, sponge, box or other air run filters are just not adequate for them.

Any or all the above will cause the problems your fish has been having. Let me know if you need clarification or have other questions........

At Your Service;
Chris Robbins