Does tank size limit fish size?

[Wandering Albatross]

Do fish grow to the size of the tank?

There is so much debate on this topic that I was hesitant to start it because of all the arguements and furniture throwing I know it will start. (there are some forums I won't put this on)

The answer to the question is a definate, maybe, well, sometimes, kinda, yes, no, and I don't really know. We can try to research it and read through scientific studies to come to a definate answer. But scientific studies usually don't mean much with something that requires a lot of time because research projects don't last for many years. Especially something for a hobby called "Ornamental Fish Keeping". We really don't need ornamental fish so there isn't mush money going toward research.

I Googled it and it seems that "most" (but not all) of the answers say that tank size does not affect the growth of fish unless it is a goldfish. I guess goldfish have a lock on stunting their own growth to the size of their tank. Well, if goldfish can do it, why can't a moorish Idol or bluefin tuna?

To get the correct answer to this question I can only go by my own experiences as I have kept way more fish than I can count for the last 60 years. A good number of them I kept for 10, 15, or 20+ years. (I also killed more fish than Starkist Tuna)

Most of the literature you will find on this will state that fish are stunted because of either inadaquate water conditions, lack of the proper diet or poor health. I will admit that those things would most likely limit the size a fish would grow. But they are not the only things as I will "try" to explain later.

A fish needs to do three things, grow, spawn and have immunity to most of the pathogens it encounters in the sea. Remember that the water the fish is in is a continuation of it's circulatory system so anything that is in the water, could easily be in the fish. It's immune system is the only thing that keeps it safe.

Fish also have to spawn and do it constantly because a fish is an animal that never dies of old age, they are all eaten alive by something bigger. If a fish gets old and slow, it gets eaten by another fish, seal, bird or polar bear. We eat the rest of them. That is why fish have so many babies, to replace all that are lost.

For a fish to acomplish those 3 things it needs the correct foods and a lot of it. Its immune system alone requires an aweful lot of calories but not as much as reproduction. Fish constantly develop eggs and even if their is no male around, they produce eggs then they re absorb them and grow new ones. This takes an enormous amount of energy. Growth is the last thing a fish needs to do so it can mature enough to lay eggs and pass on it's genes. Out of those three things, growth uses the least amount of energy and calories because fish growth is much slower than those other two things.

Fish eggs can be a large proportion of the weight of the fish and fish can spawn every couple of weeks. The immune system constantly produces slime which is a large part of it's immune system because it's slime is infused with white blood cells and antibodies and antiparisitic chemicals to repel and kill offending organisms.

What does all this have to do with the original question? Good question.

Basically all of the answers you will find about "if fish become stunted by the size of the tank" will say that the reason is lack of proper diet, or less than perfect health.

I am saying that if the fish is spawning, immune from diseases, and fairly old, it is as healthy as it can be in a tank. So that, to me, indicates that if a fish is in a tank for a number of years, it is immune from disease and is spawning, that fish is healthy so if it's growth is stunted, it is not because of lack of health.

So why all the controversy and charts indicating what size tank we should have for certain fish? The answer is actually simple but the only way we can find out the answer is by keeping a variety of fish in a tank and see if they grow to the size they would in the sea.

I have done this with many fish, salt and fresh and I can answer with a fair amount of certainty that "It depends on the fish". That is the answer.

Some fish will continue to grow no matter what we do. For instance I have kept flounders, sea robins, remora's, arowana's, scats, and a variety of catfish over many years numbers of times. Those particular fish will outgrow whatever tank they are in, and will do it very fast. I had a remora that grew so fast I could almost hear it grow. It grew over a foot in a few months.

But, (and there is always a but) I have kept many other fish for decades and they never grew very much at all. I will give examples. A hippo tang I had for 7 or 9 years in a 40 gallon tank. He stayed about 4" long. I transfered him to a 6' long tank where he lived to about 12 years old and never got much over 5". That fish in the sea can get twice that size. I had a percula clown for 12 years and for most of those years he spawned. He grew to about 2". In the sea those guys get huge. I now have a fireclown. He is about 25 years old in my 100 gallon tank. He is about 3 1/2" and his 17 year old mate is about an inch shorter. That pair spawns about once a month. As I said, if a fish is spawning, that means it is healthy and it's water conditions are healthy so if the fish is not growing, something else has to be the cause. My copperband butterfly is a few years old and has been about 5" for the last couple of years. I think he is still growing, but very slowly.

Goldfish exude substances in a tank and even in a pond that limits their size. If you put a one inch goldfish in a fish bowl, in 10 years it will be almost the same size. But if you put that same fish in a lake, it will grow to a foot or more long.

Could it be possible that other fish can do the same thing?

I really don't know, but neither does anyone else. We can read all about tank sizes for particular fish but if you personally have kept that fish in a smaller tank for 20 years and the fish was healthy and spawning and it never got very big, why would you think it needed a larger tank?

Yes, of course fish should always be in a larger tank, preferably the ocean so virtually "all" the fish we keep should be in a bigger tank. I get that.

So Tang police (I know you will be all over this like stink on a two week old dead flounder) if someone wants to put "their" own fish, that "They" bought with "their" own money. It is "their" fish and can do with it what they want. I eat fish almost every day.

Tangs almost always live in a school so, if we put "any" tang in a tank, and if you are of the mindset that fish have feelings, it won't be happy no matter what size tank it is in. From my experience most tangs are the type of fish that can remain healthy and live in a smaller tank that is many times recommended, If that tang is small when we put it in the tank. "Some" types of Tangs, like all other fish should be in a larger tank. But this hobby sometimes, either because of finances or space, will not allow for a larger tank. If you would like to disagree, that is of course fine. But before you do, get a tang and put it in a smaller tank than is recommended, keep it healthy in that tank for 12 years, then disagree and at that time let us know what were the problems you had with that tang in that tank.

Of course you also need to keep the same type of tang in a larger tank and feed it the same thing for those 12 years.

I have done this so I have an opinion on it and it is not from reading it from Google.

Now there are the people that will say it is cruel. Remember before you go there, we are all keeping fish captive against their will. They will never contribute to the gene pool in the sea. They are all in a too small tank eating something they are not used to.

I would love to keep my fish in a 10,000 gallon tank, that is not going to happen. But I would love to do that as I want the best for my fish. All my paired fish are spawning so I know they are healthy and I assume happy.

This is a fascinating post, that brings up some interesting points. I like the more direct, common sense and experience approach over the "this is how it is but I can't say why". I want all my fish to have the option to spawn if they choose to. I've been told/read that certain fish can absolutely, positively never be kept together, even as a male/female pair. Of course, tanks are a little more restrictive than oceans, so there are bound to be some changes in behavior, but if these fish could never be together, how do they spawn in the wild? Why do some tangs swim in schools in the wild, but are supposedly super aggressive to each other in a tank environment? I like looking at the science aspect, not just the popular hobbyist fluff.

My question to you is, are there any larger fish, kept in a larger tank, that you would not keep in a male/female pair or harem? (triggers, eels, wrasse, tangs, lions, groupers, angels, ect) Personally, I want large tanks understocked, so everyone, regardless of how big they get, has their own space. I'd like them to get big too. And I'd really like to keep pairs of any fish I get. In my mind, if the fish/invert is spawning, that means I'm doing something right. In theory, if the fish are well fed and "happy", they should tolerate each other as a spawning partner. I know most species (save for humans) tend to spawn when conditions are favorable. I want every fish I have to be a spawning pair, that is my end goal. 80% of the passion for me is the science, building a dynamic ecosystem with live foods, fresh greens, and regular spawnings for extra food. I've been told its extra hassle, but no one seemed to read my acknowledgement that I'm already aware of the excess work, and I'm willing to do it. It's not an "oh look, pretty fishy in an automated tank" for me. I want my fish to live the best life I can offer, which to me means giving them a mate to spawn with.

Thoughts?

Blessings :)

 

[Paul B]

My question to you is, are there any larger fish, kept in a larger tank, that you would not keep in a male/female pair or harem? (triggers, eels, wrasse, tangs, lions, groupers, angels, ect)

Again, it depends. Many, or even most fish can and do change sex and I assume, can change back. If for instance we find a pair of large groupers, they may all be male, or female. If they are all one sex, they will probably fight. But if we keep them confined, eventually some will change sex and spawn.

If they are now two different pairs, or all females, they may get along or even ignore each other.

Clowns do this all the time. At first they may fight, then one, (maybe the one who smells better) will gradually change sex and they now get along. If we add another one, they will probably fight again or even kill the newcomer. So there is no correct answer to this question.

That is my Man answer, but if I change and become a female, I may think differently even though there is no chance that will happen. :beaming-face-with-smiling-eyes:

 

[ChrisfromBrick]

i’m a big believer of keeping fish that don’t grow too large. Not sure how big a fairy wrasse gets in indonesia or wherever the hell it’s from, but I wouldn’t put a blue hippo in a 4 foot tank. Not judging those that do, as long as fish seems happy.

 

[Wandering Albatross]

Again, it depends. Many, or even most fish can and do change sex and I assume, can change back. If for instance we find a pair of large groupers, they may all be male, or female. If they are all one sex, they will probably fight. But if we keep them confined, eventually some will change sex and spawn.

If they are now two different pairs, or all females, they may get along or even ignore each other.

Clowns do this all the time. At first they may fight, then one, (maybe the one who smells better) will gradually change sex and they now get along. If we add another one, they will probably fight again or even kill the newcomer. So there is no correct answer to this question.

That is my Man answer, but if I change and become a female, I may think differently even though there is no chance that will happen. :beaming-face-with-smiling-eyes:

Sounds like it'll be trial and error then. I'm really hoping that I can find the proper balance to ensure everyone has a mate (even if that mate annoys the bejesus out of them :beaming-face-with-smiling-eyes: ) I don't plan on raising the babies at this time, but I think its good for them to have a buddy to hang with if they choose to. Everyone needs a mate, and those who don't have one want one. (unless men run away at mach 4 when you look in their general direction, then what's a lady to do.... :disappointed-face:) But at least my fish can have a chance :)

Either way, thanks for entertaining my question, I'm planning several large tanks, and I'd rather have my research done before I buy something that is wholly dependent on me for its care. By the way, thanks for having a long-winded post, I feel a little less weird about my other posts now. I try to give plenty of information so whoever is responding can see where I'm coming from. All too often, I write a paragraph worth of information for my other threads, just to have someone point out something I already covered in the main post. All responses are welcome of course, but some aren't as helpful when they totally disregard the parameters I laid out in the question. If you might spare a moment to chime in on any of those, that'd be great.

Blessings :)

 

[srcleary]

This is an older thread but I love the conversation concerning fish growth in captivity. I am a firm believer in hosting fish in a properly sized aquarium but when I here a fish “can” get so big I begin to wonder the likelihood.

Here is my experience and I feed very heavy and keep the nitrates somewhat in check for a FOWLR tank (30-60). My tank is 750g.

My Clown trigger went from 1” to 8” in 3+ years. He’s fat. I’ve heard they do grow fast.

My Mac Angel went from 4” to 9” not including streamers. He huge. Biggest fish in the tank. This was in 2.5 years.

My Dussi Tang is growing fast. 4”-8” in 2+ years. And I’ve heard they are fast growers.

But…

I have a Picasso trigger. Bought over 2 years ago at 5” and today he might be 6”.

I have a male blonde Naso. He has grown up in a tank. I got him at 5.5” three years ago and today he is about 6” . Crazy as I wanted him to grow large and he is just stuck at this size. And no one bothers him accept to nip his streamers. And he is fat.

The craziest is I picked up a Powder Blue tang over three years ago. Raised in a tank. 5” when I got him. In a 110g QT he terrorized an angel three times his size. I moved him into the display and later added an Achilles about the same size. Bad idea I suspected. And they went after each other. But today they act like a mated pair. They are together all the time and swim round and round each other. Never hurting each other. Never a big chase. And they BARELY grow! In two years they MAYBE added an inch!

My boss of the tank is my Emporer. Interesting thing is he appeared stuck at about 7” for two years. Then some other fish started catching up to his size. Like the Mac Angel. And now he is having a growth spurt and has grown a streamer!

I know some fish clearly grow faster than others but I’ll stick with, each fish is different. No hard fast rules. And for those that have super healthy fish that out grow their tank, give me a call. I’ll take them. :)

Here’s the boss. You can see how fat he is. And he is a camera hog and grunts so loud you can hear him 50’ away!