Sick Neon Tetra – Diseases and Treatment

Neon Tetras are a very popular freshwater fish, especially with beginners. In the wild Neon Tetras are known to live up to 10 years. Unfortunately in the aquarium Neon Tetras rarely live to this age. In captivity there is a higher likelihood that Neon Tetras contract diseases, become stressed or attacked by other fish. Sick Neon Tetra often perish prematurely. If your Neon Tetra is dying it is very important to identify the problem before proposing a solution. Incorrect treatment can further stress and damage the health of the fish.

In any aquarium the first check should be water parameters. It is more likely there is a spike in ammonia or temperature in the aquarium than a disease. Test the aquarium for nitrites, pH, salinity, temperature and hardness. Keep your Neon Tetras healthy and happy by keeping these parameters within range. Test these parameters weekly to ensure continued stability in your aquarium.
If the aquarium water is not an issue, your neon tetra may have other issues. Below we discuss the most likely causes for a sick neon tetra. We list these in order of most likely, to least likely.

Ich | Sick Neon Tetra

A common disease that new hobbyists often encounter is Ich. Ich can be described by its small white ball-like appearance generally around the mouth and fin region. Sick Neon Tetra are even more susceptible to catching this disease. If you notice signs of Ich on your Neon Tetra be sure to move them to a quarantine tank until symptoms clear up. For an in depth guide to Ich removal please click here.
Ich is very easily spread between your aquarium inhabitants. Remove the infected fish and place them in quarantine away from other fish. There is no need to worry as Ich is treatable. Early warning signs are sick neon tetra ‘rubbing’ against rocks, substrate and generally looking unwell.


Aquarium Cycling

Tanks with an inadequate amount of time to cycle, have a higher possibility of sick neon tetra. This is due to the elevated nitrites and ammonia that can happen when introducing new fish. Always increase bioload very slowly to prevent sick neon tetra. Add no more than 2-3 fish per week in a newly cycled aquarium.
If you do encounter sick fish after cycling it is a good idea to add Stress-zyme or commercial dechlorinator to the water. This is a short term solution to remove some of the harmful water qualities for your fish and can buy you some time. Conduct small water changes every few hours.
Watch the neon tetra and take water samples every 6 hours if you notice spikes in ammonia or nitrite. Conduct small and frequent water changes. If a mature tank is available, move the fish to the mature tank until cycling has completed.

Shock | Sick Neon Tetra

It is common for Neon Tetras to experience shock when first introduced to the aquarium. This is normal for any fish. Upon adding the fish to the aquarium ensure to keep the light off for 24 hours. It is also beneficial to limit movement around the aquarium. Avoid sick Neon Tetra by introducing the new inhabitants in a gradual manner. This will allow time for the fish to acclimatise.

Circular Swimming & ‘Flicking’ Swimming

Abnormal swimming patterns is a sign that you may have sick Neon Tetra. They will often swim in circles or twitch in the water. Healthy neon tetra will swim around the aquarium and respond to food. Sluggish or sick Neon Tetra will often ignore food added to the aquarium. Ignoring food is a immediate sign something is wrong. Check and note any improvement or decline. Unfortunately damaged neon tetra have a very low chance of survival. It is always best to be safe and quarantine any unhealthy fish. To ensure if there is 

Sinking in the Aquarium

If your Neon Tetras stuck in the bottom of the aquarium or they drift with the current this is a sign of sickness. Such behaviours imply serious health problems. First step is to always take water readings. This is usually associated with high levels of ammonia, nitrite or elevated temperatures. Other giveaways are the fish may be ‘gasping’ for breath in the aquarium and very inactive.
It is best to make a medium to large water change immediately after working out what the issue is. Keep track of the state of your sick neon tetra and look for any improvements.

Protozoan Invasion


Protozoan disease among Neon Tetras can be identified as follows: Dull color, abnormal curvature of the spine, growth of a body cyst and/or the rotting and bloating of the fins. Unfortunately this disease is contagious and can affect other neon tetra. Keeping the affected Neon Tetras in a quarantine is the best solution available. Remove them from the aquarium as soon as possible.

Medications are available and should be used. Unfortunately Neon Tetra are small and have a poor immune system once sick. Neon tetra have a low likelihood of regaining full health.

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