How to know when a fish is too big for its tank?

[One Reefing Boi]

I am going to be getting a 50gal and would love a yellow tang but understand they need a bigger system. My hope was to get a very small one (as small as they can sell really) and have it in there for awhile before it got too big I had to move it. How would I know when it is time to move it?

Or is this just not a good idea?

 

[Jay Hemdal Verified Community Expert]

The trouble is that tank versus fish size is a sliding welfare scale, there is no “hard stop” point, the issue just gets gradually worse
I’m not a big fan of small yellow tangs, the larger ones are sturdier I think.
What about a bristletooth tang?
Jay

 

[jtf74]

I am going to be getting a 50gal and would love a yellow tang but understand they need a bigger system. My hope was to get a very small one (as small as they can sell really) and have it in there for awhile before it got too big I had to move it. How would I know when it is time to move it?

Or is this just not a good idea?

You'll know when that yellow starts bullying the rest of your fish that it needs more space. I would suggest adding the yellow last as they can be pretty nasty once established. You might be ok for a year or two with one small yellow and a few other small submissive fish before the tang gets too big.

 

[egwich]

If you want a yellow tang get a bigger tank. You already know it’s a bad idea which is why you’re posting on here. Tangs are mean and when they are in a cramped tank they get meaner than hell. If a 50 gallon is as big as you can go then get fish that will be comfortable in there. Tangs need a lot of room and if you can’t provide it you’re just going to cause issues for yourself in the future.

 

[One Reefing Boi]

The trouble is that tank versus fish size is a sliding welfare scale, there is no “hard stop” point, the issue just gets gradually worse
I’m not a big fan of small yellow tangs, the larger ones are sturdier I think.
What about a bristletooth tang?
Jay

bristle tooth is cool too! just love the yellow because it is a staple (like a clownfish) but looking to add a tang more for a utilitarian purpose, not just looks. I'll look into a bristle tooth for sure!

tank is still about a month out, so that Is why I am spitballing with stocking list right now

 

[One Reefing Boi]

You'll know when that yellow starts bullying the rest of your fish that it needs more space. I would suggest adding the yellow last as they can be pretty nasty once established. You might be ok for a year or two with one small yellow and a few other small submissive fish before the tang gets too big.

ok gotcha, makes sense. Looks like I will look into a bristletooth like jay suggested or going tang-less

 

[One Reefing Boi]

If you want a yellow tang get a bigger tank. You already know it’s a bad idea which is why you’re posting on here. Tangs are mean and when they are in a cramped tank they get meaner than hell. If a 50 gallon is as big as you can go then get fish that will be comfortable in there. Tangs need a lot of room and if you can’t provide it you’re just going to cause issues for yourself in the future.

yeah I can't get a bigger tank right now, so looks like no yellow tang for this one

 

[vetteguy53081]

When the fish surpasses 1/3 the length if the side of the tank
An example is my vlamingi tang at 15” and the length of side if my tank is 48”. It alliws him swimming place all around

 

[PicassoClown04]

I wouldn’t get a tang just because you may have issues letting go of it/rehoming when the time comes. If you’re looking for algae control, a lot of other fish can serve that purpose or you can just use snails (I use snails because a lawnmower starved to death and I refuse to let that happen to another fish in my tank). Wrasses are good utilitarian fish in a system that large, and they are quite stunning. Plenty of other yellow fish if that’s what you’re looking for, but a tang in a tank that size is a bad idea. I’m thinking a 75 for even a bristletooth. Sorry for the bad news

 

[One Reefing Boi]

I wouldn’t get a tang just because you may have issues letting go of it/rehoming when the time comes. If you’re looking for algae control, a lot of other fish can serve that purpose or you can just use snails (I use snails because a lawnmower starved to death and I refuse to let that happen to another fish in my tank). Wrasses are good utilitarian fish in a system that large, and they are quite stunning. Plenty of other yellow fish if that’s what you’re looking for, but a tang in a tank that size is a bad idea. I’m thinking a 75 for even a bristletooth. Sorry for the bad news

nah makes sense -- want them to be happy so no sense on forcing it! What kind of wrasses do you like?

 

[HaveFishWillTravel]

I am going to be getting a 50gal and would love a yellow tang but understand they need a bigger system. My hope was to get a very small one (as small as they can sell really) and have it in there for awhile before it got too big I had to move it. How would I know when it is time to move it?

Or is this just not a good idea?

What I like about your question is the fact that you are thinking through your decisions before you go to the fish store and start buying. People at fish stores are usually super helpful and friendly, but they don’t always ask all the right questions and people that don’t think through their decisions end up putting livestock into their aquariums that is aggressive, grows too fast, takes over, has special needs, is not compatible, etc. Sometimes you’ll be surprised, but oftentimes you’ll be disappointed in the choices you make if you’re not somewhat careful. I can say this because I’ve done it. Cheers. JL

 

[PicassoClown04]

nah makes sense -- want them to be happy so no sense on forcing it! What kind of wrasses do you like?

I love diamond tail flashers, I think they’re gorgeous. Not my pic but

 

[Tamberav]

I am going to be getting a 50gal and would love a yellow tang but understand they need a bigger system. My hope was to get a very small one (as small as they can sell really) and have it in there for awhile before it got too big I had to move it. How would I know when it is time to move it?

Or is this just not a good idea?

When it starts stressing and bullying your other fish. You can buy captive bred ones from Biota and they are about the size of a quarter.

A small tomini tang would fit better in a 50.

 

[CavalierReef]

A colorful wrasse in a 50 can add so much to your tank. The diamond tail mentioned before is beautiful. I have a McCosker's that has personality and looks. Something to consider.

 

[mkwarner77]

I tried that with a juvinile scopa tang in my 46 gl. it didn't work, all 3 times the fish stopped eating and died within 2 weeks. they need the room to roam or they get to stressed

 

[dryworm]

I would get a small captive bred yellow tang and keep it until it becomes a problem. When it does donate it to your local fish store.

 

[CindyKz]

I would not do a tang at all in a 50 gal tank.

You can't just base tank size requirements on fish size because different species require different amounts of swimming space. Some swim all over the place (tangs, many wrasses) while some stay more stationary (think cardinalfish, clowns).

Other tank inhabitants make a difference too.

Most online retailers post guidelines. I don't know where the guidelines come from but I usually stick to Live Aquaria's just because they are the most generous, IOW give the fish the most space. Even with that you have to be mindful...I recently had to rehome a Magnificent Foxface that "should" have been fine in my 180 gal but got HUGE and was becoming aggressive toward his tank mates.

Another thing I have noticed, and this could be a weird personal thing for me. Larger fish make the tank look smaller to my visual perspective. The opposite is also true. So cramming a couple of too large fish into a smaller tank just makes it look cramped and disproportionate to me. Multiple small fish in a larger tank gives a sense of space.

Keep researching! Great job so far

 

[Timfish]

Here's an article on steriotypy behaviour to help determine if you need to rehome someone: Steriotypies as Animal Welfare Indicators

 

[Blknovass]

I’m with you would love to have that bright yellow tang but in my 60 not a good place for the fish. But if you want that bright yellow I somewhat substituted for a yellow coris wrasse. He is always on the move and is bright yellow awesome color! Really stands out in the tank.

 

[anthonygf]

I am going to be getting a 50gal and would love a yellow tang but understand they need a bigger system. My hope was to get a very small one (as small as they can sell really) and have it in there for awhile before it got too big I had to move it. How would I know when it is time to move it?

Or is this just not a good idea?

I have a yellow Tang in a 46 gallon bowfront with 30 sump for around 3 years and is happy and fat, gets along ok with 2 clowns, 2 b&w striped damsels, flame hawkfish and filefish. All are happy and thriving. Would love to get a larger tank for them but still trying to convince my wife. Ideally they should be in a bigger tank.