Saddleback and white spot can become pink or red open lesions or ulcers. Ulcers caused by bacteria come on quickly and are typically flat. This contrasts to the ulcers caused by fish TB which come on slowly and are raised bumps that slowly break open into raised edged ulcers. Ulcers in fish are most often gram-negative bacteria (columnaris, aeromonas, etc.).
Note that bacteria are often secondary invaders and ulcers are often secondary infections. Often time the primary disease is something like anchor worms or flukes. The anchor worms and the flukes break the skin of the fish and allow bacteria to enter, creating the ulcer. Bites and ramming by other fish can also break the skin and allow bacteria to enter and start an ulcer.
Treatment
Ulcers should be treated with broad spectrum antibiotics (Midland Vet Service Aqua-Mox, VetDepot Amoxicillin, Fishbiotic Ampicillin, Mardel Maracyn 2, SeaChem KanaPlex, API Fin And Body Cure) added to the food. These antibiotics are generally only available over the internet.
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.
All the fish in the aquarium should be fed a steady diet of the antibiotic laced food for at least ten days. 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.
Treatment needs to be for at least two weeks. If it is one or two fish transfer the fish to a hospital aquarium and treat. If more than two fish have the problem one must treat the whole aquarium. Note antibiotics in the food do not affect the filters so they can be left in place and operating.
If you can’t resist the urge to treat the water, remove the biofiltration media (including sponge and/or foam) in the filters and put it in an open container for the duration of the treatment. Sometimes antibiotics kill the beneficial bacteria and sometimes they don’t. In any case the filter media will denature the antibiotics. Monitor the ammonia and would do a 50% water change if it spikes above 1 ppm. Reduce the amount of food fed by 2/3 rds.
Note that if antibiotics are not available, it is quite easy to take a pill or capsule of human antibiotic and use it for fish. If it is a pill just grind it up. Just be aware that the human antibiotics are about ten times more potent than the aquarium antibiotics, so just a “smidgen” in the food is more than enough. This is a very good option for the folks in Europe or Canada, where fish antibiotics are illegal.
If one has more than one fish with a bacterial disease, one must treat the whole aquarium. This is an emergency. Don’t fool around with herbs, tree leaf oils or some ineffective treatment. Ben Ochart treated a bacterial infection with Pimafix and Melafix. They did nothing to stop the infection. He lost a lot of large beautiful fish before he stopped the infection with antibiotics. This link covers the snake oil medications such as Melafix and Pimafix:
12.4.1. Natural Medications
The entire topic of bacterial infections in tropical aquarium fish is covered in more detail in this link:
10.3.11. Treating Bacteria
Return to Diseases Menu
Return to Bacterial Menu
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Dave says
In reply to A.W….. Only treat with Kanaplex and General cure in the food in the river tank IF and ONLY IF another fish gets ulcers. Single fish get sick and die from things like ulcers all the time. One pearl danio does not an epidemic make.
A.W. says
Really glad I found this! I have a 270gal set up that I just lost one of my Pearl Danio (Danio albolineatus, not Danio margaritatus) that I have noticed wasn’t swimming well, couldn’t move the pertoral fins, it took me a day to be able to net it after watching it for a day, it had ulcers on both sides right behind the fins that slowly grew. While I am not sure how it started, I am thinking maybe it got stuck somewhere or something and damaged its sides getting free, or possibly had an altercation, though that seems less likely as it was in about the same spot on both sides. Whatever it is I was dreading having to try and remove all the fish to treat, or treat the whole tank. I haven’t seen any more ulcers on anyone else yet so I was waiting to see. This gives me another option if needed! Although instead of having to get that stuff I think I will just add some Kanaplex and either API General Cure or Prazipro (to cover antibiotics and parasites both) to a batch of Repashy Gel Food and try that since I already have all of that on hand. I have a lot of nice fish and really don’t want to have to euthanize any if I can help it! With a large planted river style set up I wasn’t looking forward to having to try and and catch a bunch of smaller fast moving fish without tearing up plants and moving driftwood. I usually only have to treat fish in quarantine when I first get them. I put them through a combination of meds to make sure nothing makes it over to my tank with the fish. This way I can just feed them some of the medicated food each day as well as regular food instead.
Thank you for posting this!
Steven Roberts says
I just terminated my infected fish because it’s a lot cheaper. I find the more fish you have and the more places you have purchased them from then you gage a higher chance of getting a fish with a hidden parasite and orca bacteria.