Red spot on rainbow fish.

[Alreadyunderwater]

My rainbow fish developed a red spot today. It seems a bit raised. He’s still swimming around. He’s by far the biggest fish in the tank so I doubt it was aggression. We’ve got 3 fancy guppies, 4 corydoras and 3 nerite snails in the tank with him. I have kanaplex but I don’t think I can treat the tank with the snails in there. Thoughts??

 

[Alreadyunderwater]

Sorry I forgot to say
20 gallons
82deg
7.9 ph (stable)
0 ammonia
0 Nitrite
5-10 Nitrate

 

[CassCats]

Tank is too small for boesemani rainbows, these boys get big, like 6-7 inches big.

That said, red puffy sores on rainbowfish is often associated with mycobacteria, aka fish TB.
However, without a microbiologist actually testing it (expensive) you won't know 100% if it is or not.

So, it's safer to assume it IS and:

Do not put your hands in the water if you have open wounds, and always always wash your hands after handling this tank.

Know that there is no cure and it is contagious to other fish. It often ends up fatal.

Do not use anything from this tank on another (water change hoses, nets, heater/filter, plants etc). It can spread between tanks. This means cannot sell or trade anything from this tank, morally.

 

[Colin_T]

Most Melanotaenia boesemani only reach 3-4 inches long. If you keep them in a 20 foot tank that is 4 feet high and live in Germany, they might hit 6-7 inches (but that was 20 yrs ago) but nowhere else in the world has seen them get that big.

Minimum size tank for them is 3 foot long and 4 foot + is better.

Red sores on rainbowfish is usually Fish TB (Mycobacteria as mentioned by CassCats). There is no cure and you should assume all the fish in the tank have it, if it is Mycobacteria.

Feeding the fish lots of plant matter (at least 50% of the fish's diet should be plant based) can help stop the ulcers appearing on the body but the infection is usually inside the fish (in or on the organs) and it eventually kills them.

If the fish bloat up overnight, stop eating, do a string white poop, gasp at the surface or near a filter outlet, euthanise it immediately. These are the symptoms you see with rainbowfishes that are dying from TB and the fish are normally dead within 24 hours of showing these symptoms. Prior to that they will be swimming around normally, showing off, breeding, and eating. Then one day you wake up and find the fish with the above symptoms.

The links below have more information about Fish TB and how to deal with it, including information about people catching it.

Questions regarding fish TB

So I have been reading things in Manual of Fish Health and this forum and have a bunch of questions regarding fish TB: 1. Why TB are common in fish from south/asian farm? 2. Can fish get TB even if you don’t buy new fish? 3. I always have cuts on my hand (I don’t know how?) How many percent can...

www.fishforums.net

TB, and effected fish…

So I’m not really understanding this, as it wasn’t around, when I had tanks 20 years ago ( or at least hadn’t been diagnosed ) Rumored to have come from Asian farming techniques… some fish species seem to be more susceptible to it than others ( my 1st experience, was with yellow axelrodi...

www.fishforums.net

wow... these look incredible... trying to look beyond TB

so, with me giving up on rainbow fish, maybe Killi's ??? assume not in the same TB history tank... but these could certainly fulfill the color urge... um... maybe with a little more economical variety...

www.fishforums.net

 

[CassCats]

Most Melanotaenia boesemani only reach 3-4 inches long. If you keep them in a 20 foot tank that is 4 feet high and live in Germany, they might hit 6-7 inches (but that was 20 yrs ago) but nowhere else in the world has seen them get that big.

Minimum size tank for them is 3 foot long and 4 foot + is better.

Red sores on rainbowfish is usually Fish TB (Mycobacteria as mentioned by CassCats). There is no cure and you should assume all the fish in the tank have it, if it is Mycobacteria.

Feeding the fish lots of plant matter (at least 50% of the fish's diet should be plant based) can help stop the ulcers appearing on the body but the infection is usually inside the fish (in or on the organs) and it eventually kills them.

If the fish bloat up overnight, stop eating, do a string white poop, gasp at the surface or near a filter outlet, euthanise it immediately. These are the symptoms you see with rainbowfishes that are dying from TB and the fish are normally dead within 24 hours of showing these symptoms. Prior to that they will be swimming around normally, showing off, breeding, and eating. Then one day you wake up and find the fish with the above symptoms.

The links below have more information about Fish TB and how to deal with it, including information about people catching it.

Questions regarding fish TB

So I have been reading things in Manual of Fish Health and this forum and have a bunch of questions regarding fish TB: 1. Why TB are common in fish from south/asian farm? 2. Can fish get TB even if you don’t buy new fish? 3. I always have cuts on my hand (I don’t know how?) How many percent can...

www.fishforums.net

TB, and effected fish…

So I’m not really understanding this, as it wasn’t around, when I had tanks 20 years ago ( or at least hadn’t been diagnosed ) Rumored to have come from Asian farming techniques… some fish species seem to be more susceptible to it than others ( my 1st experience, was with yellow axelrodi...

www.fishforums.net

wow... these look incredible... trying to look beyond TB

so, with me giving up on rainbow fish, maybe Killi's ??? assume not in the same TB history tank... but these could certainly fulfill the color urge... um... maybe with a little more economical variety...

www.fishforums.net

My friend had his boese in a 135g and yes definitely were 6 inches+
Another person I know has had massive ones too? 4-5 inches is around the average, but 6-7 inches is not unusual still either.


Plus rainbows are very active. They take years to grow as rainbows can be very slow growers, but boese do reach large size. This is very false information here a 4 footer is the minimum for boesemani and other large rainbows. Id only consider a 3 footer for ones such as praecox, sahulensis, maccullochi... always house as if it will reach max size instead of settling for "it doesn't normally grow that big". Your advice is insinuating fish grow to their environment which we already know is harmful to their health and wellbeing.

Not to mention, rainbowfish are schooling fish, so a tank smaller than 4 feet isn't going to allow proper space to school, interact, etc without stress. They are already prone to swimming into glass and getting nerve damage as well, plus being at risk of jumping in too small of a space. To advise a 3 foot minimum for a potentially larger growing schooling fish is a surprising bit of advice that goes against the quality standard advice of this forum.

 

[Colin_T]

@CassCats, you must have had different M. boesemani to what we have in Australia because I have never seen them get to 6 inches here, let alone bigger and I had them for 20 years. The only time I have seen big M. boesemani was in a photograph from Germany back in the late 1990s, which was hard to really put a size on them and we took the photographer's word. But they were in a huge tank and looked to be a good size.

 

[CassCats]

Here's a friend with a large boese a friend had

And another in their 135g

Yes there's different localities, but most what we get are simply aquarium strain boese and they get big.

These are not fish suitable for 3 foot tanks. Or less at that.

Shared with permission.

 

[Alreadyunderwater]

Thank you for all the replies. When we acquired this fish we had a 75 gallon tank and he had friends. Unfortunately we had two 75 gallon tanks spring leaks on us in less than a year. I was ready to give up on aquariums but my children were crushed so we kept a small number of fish in the smaller aquarium but we are continuing to run into so many obstacles. I did not have fish TB on my bingo card

We will continue to observe Cricket the rainbow fish. He’s the only remaining fish from our large tank. We will be cautious and aware of the hazards of re-homing etc. thank you!

 

[CassCats]

Thank you for all the replies. When we acquired this fish we had a 75 gallon tank and he had friends. Unfortunately we had two 75 gallon tanks spring leaks on us in less than a year. I was ready to give up on aquariums but my children were crushed so we kept a small number of fish in the smaller aquarium but we are continuing to run into so many obstacles. I did not have fish TB on my bingo card

We will continue to observe Cricket the rainbow fish. He’s the only remaining fish from our large tank. We will be cautious and aware of the hazards of re-homing etc. thank you!

Ahhh so there's circumstances here, that's understandable and definitely viable reasons.

Especially be careful with the open wounds on yourself or kids if they touch anything with the tank. It's rare, but there are certain strains of mycobacteria (fish TB) that can spread to people and easiest way is through open wounds on the hands. If you get any sores on the skin that are stubborn and slow to heal, make sure to let your doctor be aware you may have potential mycobacteria in your home aquarium. No treatment for fish, but there's treatment for humans, though it's a lot. However, chances of it spreading are very very low as it is, but still good to be mindful of safe handling.

 

[Alreadyunderwater]

Here's a friend with a large boese a friend had
View attachment 350976

And another in their 135g
View attachment 350977

Yes there's different localities, but most what we get are simply aquarium strain boese and they get big.

These are not fish suitable for 3 foot tanks. Or less at that.

Shared with permission

Ahhh so there's circumstances here, that's understandable and definitely viable reasons.

Especially be careful with the open wounds on yourself or kids if they touch anything with the tank. It's rare, but there are certain strains of mycobacteria (fish TB) that can spread to people and easiest way is through open wounds on the hands. If you get any sores on the skin that are stubborn and slow to heal, make sure to let your doctor be aware you may have potential mycobacteria in your home aquarium. No treatment for fish, but there's treatment for humans, though it's a lot. However, chances of it spreading are very very low as it is, but still good to be mindful of safe handling

Ok I am curious if it is the mycobacteria would you expect it to improve? Cricket is looking better. Photos attached. I can tell where the redness was but it seems to be getting better. The only thing I’ve done is regular cleaning and I added about a tablespoon of salt to the 20 gallon tank.

 

[Colin_T]

maybe it was just a damaged scale or small wound then. hopefully that's all it is

 

[CassCats]

If it's improving, you lucked out and it's likely not mycobacteria. Great news on the improvement still, good practise to wash hands after to be safe too.