Red spot and bump on neon tetra

( Picture of dead fish warning) Hello. I began quarantining a few neon tetras the other day. One of them stopped eating and was floating to the top corner of the tank, which seems to be the most clear sign that something is wrong. I saw that it’s belly had a sharp bump on it with a red spot and that it seemed to be gasping for air. I increased water agitation in case the gasping was an oxygen problem (although the other fish are acting fine), but I’m worried about it’s stomach. Anyone know what’s wrong?

Update: unfortunately he passed away. I took an up-close picture of the stomach, is this anything I should be treating my other fish for?

 

This is the most stressful time of the fish's life being moved from the fish farm to the LFS and then to your tank. Water chemistry is inevitably different, packaging, transportation etc.

Immune systems are suppressed and any weaknesses are exposed.

I'm not sure what this one died of but hopefully not the usual Columnaris, which looks like white patches on the body (skin, muscle) and fins (and unseen on the gills where it can often do the most damage).

Columnaris is the most common ailment in this situation. It is a bacteria that lives on the fish skin and can escape normal immune system control when fish are stressed. The bacteria then begin to feed on the fish itself.

In good aquarium conditions fish received with problems (even moderate Columnaris) can often recover but it may take weeks or months in my experience.

Often with small fish they may be too far gone by the time ailments are noticed. It is in their interest to hide the fact they are unwell otherwise predators would pick them off.

I am not convinced that medications are helpful in these situations as they do not usually improve water quality.

Perhaps antibiotics or other chemicals can help treat Columnaris without affecting the beneficial bacteria but I realise I have little experience of using them in aquaria.

 

This is the most stressful time of the fish's life being moved from the fish farm to the LFS and then to your tank. Water chemistry is inevitably different, packaging, transportation etc.

Immune systems are suppressed and any weaknesses are exposed.

I'm not sure what this one died of but hopefully not the usual Columnaris, which looks like white patches on the body (skin, muscle) and fins (and unseen on the gills where it can often do the most damage).

Columnaris is the most common ailment in this situation. It is a bacteria that lives on the fish skin and can escape normal immune system control when fish are stressed. The bacteria then begin to feed on the fish itself.

In good aquarium conditions fish received with problems (even moderate Columnaris) can often recover but it may take weeks or months in my experience.

Often with small fish they may be too far gone by the time ailments are noticed. It is in their interest to hide the fact they are unwell otherwise predators would pick them off.

I am not convinced that medications are helpful in these situations as they do not usually improve water quality.

Perhaps antibiotics or other chemicals can help treat Columnaris without affecting the beneficial bacteria but I realise I have little experience of using them in aquaria.

Thank you so much for the detailed response! Thankfully the other fish aren’t showing any signs of sickness so far. I’ll increase water changes to hopefully improve the conditions. I have some Maracyn on hand, do you recommend I treat the others or would water changes alone improve their health?

 

Good water quality is essential to keeping fish healthy. Do all you can to promote it but don't go overboard. I change a third of the water each week for my tetras but I have abundant plants.

I'd only medicate for a specific disease e.g. whitespot (ich). When I unwittingly purchased Neon Tetras that had Columnaris I lost a few but I did not medicate and their health gradually improved until all symptoms were gone. It is much better to purchase fish from a good source where they do not have advanced Columnaris or other diseases. Some retailers are able to acclimatise them well and avoid problems. I have found an LFS that has mastered this, but others just remove many dead fish from the tanks each day before opening their shop.

Good quality food (but not too much) is also important for water quality as it is digested well so does not spoil the water. Neon Tetras require half a flake per day to survive, maybe a whole flake when growing, so feed the minimum whilst ensuring they all feed.

Neon Tetras are farmed. The natural selection pressures that keep the species fit and sturdy in the wild are not all present at the farm. Weak individuals are able to breed and are sold to the consumer not removed from the gene pool. Diseases (or strains of diseases) that are not found in the wild are present in the fish farms. Hopefully the rest of your fish are healthy and you only lost the weakest individual.

 

Good water quality is essential to keeping fish healthy. Do all you can to promote it but don't go overboard. I change a third of the water each week for my tetras but I have abundant plants.

I'd only medicate for a specific disease e.g. whitespot (ich).

Good quality food (but not too much) is also important for water quality as it is digested well so does not spoil the water. Neon Tetras require half a flake per day to survive, maybe a whole flake when growing, so feed the minimum whilst ensuring they all feed.

Neon Tetras are farmed. The natural selection pressures that keep the species fit and sturdy in the wild are not all present at the farm. Weak individuals are able to breed and are sold to the consumer not removed from the gene pool. Diseases (or strains of diseases) that are not found in the wild are present in the fish farms. Hopefully the rest of your fish are healthy and you only lost the weakest individual.

I will focus on keeping good water quality then! The other fish still seem fine, and yes- it was the smallest of them that died. He seems a bit unhealthy when I purchased him but I was hoping to give him a chance. Thank you for the feeding recommendations as well.