When a fish gets red skin blotches invariably everyone on social media will immediately comment that the fish has ammonia poisoning. They are generally wrong.
There are two distinct types of red blotches seen on fish:
- Blood red blotches. These are hemorrhagic septicemia caused by bacteria. These are what are seen in the home aquarium.
- Crimson red blotches, typically seen in fish which have been in their shipping bags for four or more days. This is carbon dioxide/ammonia poisoning, caused by carbon dioxide levels which have exceeded 40 ppm and/or ammonia exceeding 5 ppm.
These are the red blotches of septicemia
This is what one will see in late shipped bags of fish:
Most cases of hemorrhagic septicemia are gram negative infections and are best hit with a broad-spectrum antibiotic effective against gram negative bacteria. These need to be obtained from the internet. They include Thomas Labs Fish Mox, Midland Vet Service Aqua-Mox, VetDepot Amoxicillin, Fishbiotic Ampicillin, Mardel Maracyn 2, SeaChem KanaPlex, Thomas Labs Fish Min and Thomas Labs Fish Doxy.
Bacterial infections are most effectively treated with antibiotics in the food. Many believe (and the instructions on the antibiotics say!) that antibiotics need to be added to the water. They are simply incorrect. This controversial topic is covered in the following link:
12.5. Fish Don’t Drink
It is easy to make medicated food. Heat 1/4 cup water (two ounces or 58 milliliters, not a lot) in the microwave. Then blend seven grams of plain animal derived gelatin (Knox gelatin, one packet) into the hot solution with vigorous stirring. Take two tablespoons of dry commercial fish food (pellets or flake) and mix it with just a little of the hot water/ gelatin mixture. Add hot water/gelatin until you get a paste like consistency. If it gets too watery just add more food. To get gel food to float simply mix in a little whipped cream at this point.
Then add just a “smidgen” (roughly 1/16 teaspoon, a 1% to 2% addition) of medication to the mud. If you are using more than one medication mix the medications together, then use just a “smidgen” of the mixture. If you are using a packet of medication, take just a “smidgen” of the packet contents. Mix and mash the whole mass thoroughly. Spread it out into a pancake about 1/8th inch (3 mm) thick on a plastic film or a plate. Then put in the refrigerator. If you plan on keeping it for more than two weeks put it in a small plastic bag and freeze.
Feed this to the fish. These antibiotics are FDA approved for use in humans so they are extremely safe. Note that the exact amount of medication which goes into the food is not very important. Antibiotics can be overdosed pretty much with abandon as they are only toxic in large doses over a period of months.
If one is in Canada or Europe it becomes difficult to treat septicemia as aquarium antibiotics are not available. The best course in these countries is to grind up a human antibiotic pill and add it to the food. Just note human antibiotics are much stronger than the aquarium antibiotics so they only need a tiny “smidgen” of antibiotic being added to the food.
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Dave says
In reply to Sara ….. That is descriptive of Fish TB. You have symptoms normally caused by a bacteria (TB is a bacteria) which don’t seem to bother the fish very much (common with TB) and which have existed for a long time (again, common with TB). There is no real treatment for fish TB other than ultraclean UV treated water. So stop treating and just let him live out his life. He could live a very long time. If you want to, try putting him into a community tank that has a UV unit. It might help. It might also do nothing.
Sara Grimaldi says
My larger goldfish is 3 years old and he’s born in one of my tanks (I keep fishes since 35 years).
After one year he started to have 1-2-3 blood streaks on his tail. I treated him with every remedy I found in shops, internet and youtube (but I’m in Europe, I used what I found), and nothing ever worked.
The bloody tail is like that since *2 YEARS*. Sometimes it gets better and I don’t know why: the improvement soesn’t happens after some different-than-usual water change, or after a significative massive plantation, or after a new filter is set… it just happens but after a couple of days it gets worst than before.
Now (since months) he has red blotches, sometimes they are darker, sometimes more light in color and bright. The strange thing is that no other fish has *nothing*. They are all very healthy. (more than 20 fishes at the moment, in 3 different tanks).
every 3-4 months I try to make the situation better for him by using products against bacteria, because I guess it’s something about internal bacteriosis. He’s now in a quarantene tank, with 2 types of salt, medicated food, and in the middle of a first cycle he was slightly better, but after a week: worst. I change the water every day, half from the old tank, half new, I add salt and medicines again and so on.. he’s always the same or worst. A bit depressed on the bottom, but always hungry and happy to see me.
I don’t know what to do. I have no antibiotic for humans because a doctor have to prescribe them to you after a visit. I have some paracetamol, an anti inflammatory, and things like Sera Pond Omnipur S.
Is it a chronic thing? A congenital thing? I put him in the 300 liters tank (with a 1000 liter filter) and he didn’t improved. I put him in the 160 l (with a 500 liter filter + two air sponge filter) where fishes older than him thrived: nothing. Every tank is heavy planted. Temperature, nitrites, as I said, everything goes well since years. His best friend (they gave us a lot of babies) is a female I have since 8-9 years. She’s old and she’s going white, but she never had no blood or ragged fins or illness, she’s sane as their babies are. He’s the only one with such a problem. I don’t know what to do.. thank you for any advice.