Neon Tetra Disease Treatment (Melafix)

Neon Tetra Disease is a mysterious disease that strikes mainly neon tetras, but other fishes are also susceptible to it. The online opinion is that there is no cure, some even suggest euthanizing the poor tetra to avoid it spreading.

Neon Tetra Disease Signs

The signs of neon tetra disease include some of the following classic symptoms:

  • Loss of color in a patch of skin
  • Fin rot
  • Curved spine in advanced cases

Our neon tetra exhibited two of the classic signs (white patch and loss of color near the head), and fin rot near the tail. For more pictures and graphics of the symptoms, see the video below.

Neon Tetra Disease Cure (Melafix?)

We seem to have stumbled upon a cure for neon tetra disease using Melafix. Melafix is a herbal fish medicine based on tea tree oil, and is targeted at bacterial infections of fish.

After one dose of Melafix, and over 9 days, our neon tetra has shown a dramatic improvement (as seen in video below). The white patch of loss of color is gone, and the fin rot near the tail is gone as well. In addition, the fin tissue near the tail has grown back to normal levels.


API Aquarium Pharmaceuticals 11J Melafix, 16 oz. (11J)

In the video below, our neon tetra was cured (after around 1 week) from Neon Tetra Disease, after dosing Melafix.

Neon Tetra Disease Cause

As mentioned before, there is almost no information on neon tetra disease, even though it is a very common disease of neon tetras. Some say that it is caused by a Microsporidian parasite called Pleistophora hyphessobryconis.

There is also a closely related disease called “False Neon Tetra Disease”, which is caused by bacteria. The symptoms are so close that it is impossible to tell apart the two diseases without a microscope in a laboratory.

According to famous fish keeper Cory from Aquarium Co-op, Neon Tetra Disease is caused by Mycobacterium, which also causes fish tuberculosis.

Neon Tetra Disease Cure

Based on our experience, Melafix certainly seemed to cure the Neon Tetra Disease. Then again, theoretically Melafix works against bacterial diseases but not parasitical diseases. Hence, it may work for the cases of Neon Tetra Disease which are caused by bacteria, but not for those that are caused by parasites.

Neon Tetra Bloated

Neon Tetra Bloated (Constipation)

One of my neon tetras is bloated/constipated. It has trouble sinking, it is swimming heads down and tails up. Hopefully it does not progress to the dreaded swim bladder disease or dropsy. Possible reasons is that it could have eaten the lion’s share of the TetraMin flake food the day before. I tried dosing Melafix (do not have any other suitable medication). I find that flake food tends to make neon tetras bloated (they may swallow air at the surface), but usually it subsides within a few hours. This tetra has been bloated for one full day, which is quite abnormal according to my experience.

Neon Tetra Bloated Recovery

Good news! The neon tetra recovered from bloat! Its stomach is noticeably more normal sized (previously there was a small lump). I am not sure if it was due to the Melafix or not. It is swimming normally now.


Update: I found out that one way to prevent neon tetra from getting bloated, without pre-soaking pellets and flakes, is to scatter the floating pellets in a wide area around the tank. This allows more time for the pellets to absorb water while the neon tetras are searching around. I found that this is much better than feeding through the “feeding slot” area at the top of my tank lid.

Another advantage is that slower fish can also get a better chance at eating the pellets while the fast neons are swimming around searching for their food. If I drop the pellets in a small area, it is likely that a few neon tetras will gobble up all the food, leaving none for the rest (and those neon tetras will end up bloated).