Help!! Black goldfish that shouldn’t be black.

Help! I used to have goldfish but I always had a 30 gallon tank which I had for 7 years. My kids got carnival fish and my husband bought a 2 gallon tank. Well the fish started to turn black and unhealthy so I did everything I could think of and they still aren’t getting better. I went and bought water and everything thinking it was coming from my two water. What can I do to get these fish healthy?

 

That doesn't sound good. Can you give us some more information?

What are your water parameters?
What is your water change schedule?
What do you mean by acting unhealthy?
How fast did he start changing colour?
How long have you had this fish?
Did you cycle the tank?

2g is small for a goldfish, do you still have a larger tank to put him in?

 

Welcome to fishlore

that looks like a common goldfish to me, they need 75-100gal each then another 30gal for each fish added.

I assume you live in the USA?? if you can i would reccommend you go to Tractor Supply and purchase a stocktank bigger then 125gal for the 2 goldfish. You can use it as a patio pond or make it an inground pond your choice you just need a big tank.




Also do you understand the nitrogeon cycle ? if not i suggest reading up on it and you may have to do a fish-in cycle.

 

Judging from the pictures of the fish it's not a genetic color change as the fish gets older, the most likely cause of this is ammonia burns, bad enough to burn the skin, not bad enough to burn the gills severely and kill the fish. You probably caught it in time.

You should test the water for ammonia, see if it's still there and getting worse and water change to keep it as low as possible, but this looks like healing to me and not new damage. I "think" you caught it early enough, to where it's damaged the skin, but hadn't gotten infected and now the damaged skin is healing. Keeping the tank clean is most important so they don't get secondary infections from the burn damage, keeping ammonia low to non-existent is also real important, it will kill the fish if it gets bad enough.

If it were black spot disease it would be lots of black parasitic bumps. The fins and stuff look well shaped and not damaged so I don't think it's a parasite that did it.
Although the fins look good, around the head looks rough like damage.

Yeah this looks like ammonia burns as the most likely reason for the color change.

You've kept goldfish so likely I don't need to tell you but will anyways, those look like comet goldfish and if taken care of can reach 9" in 2 years, 12" in about 3 years.
You'll need a bigger tank in the long run if they survive.

I have to guess since carnival goldfish and kind of a surprise, the tank isn't cycled.
If that's the case you need
1. an ammonia test kit as a bare minimum better if you can test ammonia, nitrites, nitrates and pH.
and 2. in my opinion a product called seachem prime to treat the water with to make it through the cycle and avoid ammonia damaging or killing these fish.
You'd use the prime and dose 2 drops per gallon of water, and test for ammonia or Nitrites. Any time they hit 0.50ppm, do a water change of 50% to lower the ammonia to 0.25 ppm, and then dose the new gallon of water added by 4 drops. The prime should be redosed every 24-48 hours or per the gallon of new water added until tests stop showing ammonia or nitrites for a week to be safe. Later, the nitrate test can be used to monitor the build up of nitrates and as a result bacteria and funguses that go along with nitrates being higher and the water quality declining due to waste build up in the tank, useful to know to avoid bacterial or fungal infections.

This product "prime" will protect the fish for up to 1ppm of ammonia or nitrites, until it's cycled and then the cycle will take over dealing with the ammonia and nitrites from there. I only recommend it because I use it myself and totally trust it to do what I'm saying it will do. It also neutralizes chlorine in tap water.

Because I believe the tank is not cycled and you don't have a backup or quarantine tank that's cycled, I'm going to recommend to NOT use antibiotics to avoid a secondary bacterial infection in the burns. Antibiotics will kill the cycle off also, and thats not going to help you out of this bad situation.

Instead I'm going to recommend a water change of 50% daily regardless of test results and keeping the tank clean of waste and uneaten food and low ammonia. This will keep bacteria counts low, the ammonia low, and the fish's immune system and healing factor high. If the ammonia or nitrites go up to 0.50 ppm at some point during the day, a 2nd 50% water change that day might be necessary, but as time goes on the cycle will take over and that work will become less. Just resign yourself to a morning 50% water change, and then testing again maybe at 6 hours and 12 hours to get an idea how much is showing up and how fast.

And the product seachem prime acts as the safety net for you. It removes chlorine from the water and protects for 1ppm of ammonia and binds it as non-toxic dosing as directed. It gives some space if you are wrong about how much ammonia or Nitrites appear and how fast they appear.

Doing this should get the tank cycled and the fish the best shot of making it through this and healing, and not getting worse or infections in the burns.

Because of the water changes that need to be done, it's a good thing the tank is small. 50% water change is 1 gallon. It's quick and easy to do. You do need a bigger tank for them, but let's treat this one as a hospital tank and get it cycled and liveable and the fish healed and you can worry about the bigger tank in a month or so when things for the fish are much more improved, this tank cycled, and they are looking much better.

 

Carnival's should stop giving goldfish away as prizes