Boeseman's rainbowfish in 29g tank?

I recently accepted to take in a collection of fish a friend told me about that someone was trying to get rid off because they got tired of them. I was told they were about two dozen small fish (tetras, guppies, corries, minnows), so I put them in a 29 gallon tank. What I was not expecting was also receiving a Boeseman's rainbowfish. He's young, so about two inches in length, but I know they grow quite a bit (I've never had one). He gets along well with the other fish, and everyone seems very healthy and happy. From what I've read, these rainbowfish need a 50 gallon tank. I want him to thrive, but I don't have the money or ability to care for a 50 gallon tank. Is it completely ridiculous for me to hope he'll be okay remaining in this tank? The only other tanks I have are 10 gallons, so I could possible put some of the other fish there to make it less crowded (I have 10 tetras, 3 minnows, 2 guppies, 2 lambchops, 2 corries).
If he absolutely needs a larger tank, do you have recommendations of how to rehome him? I don't like rehoming any pet, but I want the best for him - and the rest of the tank mates. Are there local fish rescues that could put me in contact with someone who can take care of him?
Thank you for the help!
(also this is my first post here so please me kind if I put this in the wrong place or something)

He's beautiful, and it was kind of you to take in your friends fish, and to come to ask how best to give him a good life

I'm sorry, but I think it would be better to re-home him. It's not just the size of the tank, it's the fact that rainbows are shoaling fish. They need to be in a group with others of their same species, which as you've discovered, means they need a big tank for a proper shoal of 6-8 of them.

You could call of your local fish stores, and ask them to let you know when they get a group of Boeseman's rainbows in, and if he can join them. As you've said, he's a young fish, so a life without friends wouldn't be very fair to him, he's young enough to fit in with others and lead a long life in the right size tank. Or you can look in forums like this for someone who already has rainbows and see if they can take him to join theirs. I know that @Stan510 keeps a rainbow fish tank, he would likely have better ideas

The cories, minnows and lambchops are also schooling fish, so it would great if in time, you could up their numbers so they have at least six of the same species.

The good news is that there are beautiful, smaller species of rainbow fish that could work really well in a 29 gallon, so you may still be able to keep rainbow fish later on, if your water hardness is suitable

AdoraBelle Dearheart said:

He's beautiful, and it was kind of you to take in your friends fish, and to come to ask how best to give him a good life

I'm sorry, but I think it would be better to re-home him. It's not just the size of the tank, it's the fact that rainbows are shoaling fish. They need to be in a group with others of their same species, which as you've discovered, means they need a big tank for a proper shoal of 6-8 of them.

You could call of your local fish stores, and ask them to let you know when they get a group of Boeseman's rainbows in, and if he can join them. As you've said, he's a young fish, so a life without friends wouldn't be very fair to him, he's young enough to fit in with others and lead a long life in the right size tank. Or you can look in forums like this for someone who already has rainbows and see if they can take him to join theirs. I know that @Stan510 keeps a rainbow fish tank, he would likely have better ideas

The cories, minnows and lambchops are also schooling fish, so it would great if in time, you could up their numbers so they have at least six of the same species.

The good news is that there are beautiful, smaller species of rainbow fish that could work really well in a 29 gallon, so you may still be able to keep rainbow fish later on, if your water hardness is suitable

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Thanks for your input! I figured re-homing was the best option. Before I knew about him, I had planned on increasing the school sizes of the others! Thanks for letting me know he shouldn't be alone. I'll reach out to my local aquariums and see if they have suggestions or are willing to take him.

I appreciate your help! Thanks so much!

pkenziep said:

Thanks for your input! I figured re-homing was the best option. Before I knew about him, I had planned on increasing the school sizes of the others! Thanks for letting me know he shouldn't be alone. I'll reach out to my local aquariums and see if they have suggestions or are willing to take him.

I appreciate your help! Thanks so much!

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You're welcome! Hope you stay and enjoy the forum, and share some photos of your tanks! They sound lovely

Before doing anything...I have a somewhat different approach to these situations. Males of Melanotaenia boesemani can attain 4.3 inches, and female 3.2 inches, and being a shoaling species there needs to be a group of at least six, but with a few more the males will be truly beautiful in colour. Now, this is the proper care requirement for this species.

When one "inherits" a group of fish that are clearly not being maintained correctly, there are a couple options depending upon circumstances. If these fish were acquired by the former "aquarist" fairly recently, say a few months, it should be possible to separate them out with additions in suitably-sized tanks. However, if they have been together for longer, this may not be in the fishes' best interest. I have no idea how these fish are now coping with their (former) adverse condition. This does cause stress, and that has further implications. For example, it is possible that one might move the lone rainbowfish into a 90g tank let's say with a group of seven or eight of the species, and this lone fish might become a holy terror, or the others might turn on this one.

In other words, sometimes it is kinder and more humane to leave things as they are. Obviously you do not have tank space for what would be ideal, so rather than euthanize this fish or ship it off to another situation which for all we know may be as bad or worse, if possible it may be advisable to see how things go. The other shoaling species named need larger groups too, so this just gets compounded.

This is comparable to what happens when a group of fish begin dying off from old age, and one is left with one or two survivors--and it is really amazing how long a sole survivor can live on--and if one does not want to acquire more of this species for whatever reason, leaving the survivors to live out their days in relative comfort and familiar surroundings seems preferable to subjecting them to less than ideal conditions with new companions that will be much younger and may or may not accept the survivor.

@Byron is right in this too. For a moment I was a bit crushed, like "Byron disagrees with me!" but on re-reading, I realised I agree on most of it.

I disagree slightly when it comes to the rainbow fish because you've said he's young and small, so I assumed the previous owner hadn't had him for long, and that he he would be better able to adjust to joining other rainbows. But, that clearly would depend on the new set up he'd be moving to, and whether he could adjust and be accepted.

But I wholeheartedly agree that with an inherited tank of older fish, even a less than ideal mix, is often best left as it is. That's the same principle I'm following with my dad's nightmare tank since I took over maintaining it a year ago. It's a nightmare mix of the wrong school sizes and hard/soft water fish, but most of them are elderly, so I wouldn't give them away to live in new schools where they likely wouldn't be readily accepted and would be much more vulnerable to the stress of being moved. I'm also not buying more cardinals/glowlights/black neons etc, because the water is wrong for them, and I believe it's better to let the elderly remains of the school die off where they are, and not buy any young ones to bump up their school numbers, since that would condemn the young ones to live out long lives in the wrong water, and the cycle would never end.

However if any of the fish in my dad's tank were young and recently acquired, I'd be trying to find a good home for them. He also has only two bronze cories that are relatively young and the water is okay for them, so I recently bought four more to bump their school up.

So I both agree and disagree with @Byron , but he's a very wise and knowledgeable man with a great deal more experience than I have, so his views carry more weight. Personally I would try to find a really nice home for the rainbow, and assess the other schools on a case by case basis. If you want to continue keeping that species, and they suit your water and tank size, then by all means add more. But if you'd prefer to be keeping other fish but are willing to let them live out their lives with you, even with the less than ideal school numbers/tank size/water parameters, then you'd be doing a great kindness too.

Byron said:

Before doing anything...I have a somewhat different approach to these situations. Males of Melanotaenia boesemani can attain 4.3 inches, and female 3.2 inches, and being a shoaling species there needs to be a group of at least six, but with a few more the males will be truly beautiful in colour. Now, this is the proper care requirement for this species.

When one "inherits" a group of fish that are clearly not being maintained correctly, there are a couple options depending upon circumstances. If these fish were acquired by the former "aquarist" fairly recently, say a few months, it should be possible to separate them out with additions in suitably-sized tanks. However, if they have been together for longer, this may not be in the fishes' best interest. I have no idea how these fish are now coping with their (former) adverse condition. This does cause stress, and that has further implications. For example, it is possible that one might move the lone rainbowfish into a 90g tank let's say with a group of seven or eight of the species, and this lone fish might become a holy terror, or the others might turn on this one.

In other words, sometimes it is kinder and more humane to leave things as they are. Obviously you do not have tank space for what would be ideal, so rather than euthanize this fish or ship it off to another situation which for all we know may be as bad or worse, if possible it may be advisable to see how things go. The other shoaling species named need larger groups too, so this just gets compounded.

This is comparable to what happens when a group of fish begin dying off from old age, and one is left with one or two survivors--and it is really amazing how long a sole survivor can live on--and if one does not want to acquire more of this species for whatever reason, leaving the survivors to live out their days in relative comfort and familiar surroundings seems preferable to subjecting them to less than ideal conditions with new companions that will be much younger and may or may not accept the survivor.

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This is such great information! Thank you so much for taking the time to explain all of that. I appreciate it.

I think that in this case, he'll be fine to transition elsewhere. I just visited a nearby aquarium store to scope them out, since I'd never been there. I talked with the manager and they take extremely good care of their fish and only sell to clients who know how to properly care for them. Every fish there was so colorful and healthy-looking! The manager is happy to take my buddy and, after quarantining him, will make him available.

The rainbowfish and all of the others seem extremely young (the tetras are so tiny! They're maybe 1/2"). I'm pretty sure the lady I took them from just had an impulse shopping spree at Petco.

Thanks to both of you for your advice! I appreciate your help so much. My rainbowfish send his thanks as well!

Welcome, and thank's for the questions.
What great thread content!
These are the challenges faced by responsible aquarists. I enjoyed the responses.
I am troubled when I lose fish and the remaining group is small. Get a couple of those scenarios and then you're dealing with the worries of community tank dynamics.
You are blessed to have that LFS, I have a good one, too, and have seen fish I return get chosen again by someone else.
Feels great!
Stick around; we want pics ☆

Just saw this now.
They are not small fish. They also change proportions so that slender 2" fish will become a deep bodied and surprisingly wide body about 5" I've found myself re scaping to give the many Rainbows I have more room to play or just get away from the crowd as some do a few hours a day.
If you can never find him another home,but continue to give him good TLC and he gets over that 4" mark at 2 years or so..at least the larger Rainbows are more sedate-lol. Young ones are like Danio's constantly on the move...that changes.

Stan510 said:

Just saw this now.
They are not small fish. They also change proportions so that slender 2" fish will become a deep bodied and surprisingly wide body about 5" I've found myself re scaping to give the many Rainbows I have more room to play or just get away from the crowd as some do a few hours a day.
If you can never find him another home,but continue to give him good TLC and he gets over that 4" mark at 2 years or so..at least the larger Rainbows are more sedate-lol. Young ones are like Danio's constantly on the move...that changes.

Click to expand...

Thanks for the info! I did end up giving him to my LFS. He’s in good hands there and is currently in a huge tank with others.