Growth rate vs max size potential

[neutrino]

All fish grow their entire life. Whether it slows down or not or how long it takes to slow down are all factors. But i have yet to read on a fish that doesnt have indeterminate growth. Most fish just put on mass after certain lengths but to say they stop growing is simply untrue

That may be common wisdom, or internet wisdom, but I've kept hundreds of fish and tested this and direct observation says different with various species. For example, a 5.5-5.75 inches O. lithobates at 3 years is still 5.5-5.75 inches at 5-10 years-- I've measured, if they've continued to grow it's virtually undetectable-- a few millimeters? Tank size doesn't change it, I've kept them in 4ft tanks and lightly stocked 6 ft tanks-- no difference-- and in fact, they don't get larger than that in the wild with a whole lake to grow in. And, no, if fed properly they don't keep adding girth, if they did this would be abnormal and lead to health problems (some species add girth, many don't).

Same is true of other species I've kept which reach a max size where growth beyond that is negligible at most, otherwise non-detectable-- I've measured it. Some that continue growing beyond a certain point do so at a very slow rate. I have a 15 yr old L260 pleco, still healthy and active, a little less than 4". Growth from year 3 years to now-- 12 years-- is 1/2 inch. I have a 14 yr old male kapampa gibberorosa, growth from 5-6 years to now is 1/2 inch, some individuals may add a little more. Not that I've defined a 1/2 inch limit of growth for older Cyphotilapia, but growth beyond a certain age is limited to negligible, not meaningful in terms of tank size.

I've read article statements that "most" fish grow all their lives as well as statements that "all" fish grow all their lives. "All" is almost certainly an extrapolation that does not include a study of all species, which would be a virtual and practical impossibility. However, for the moment let's assume "all" is technically true. If so, in many species this growth becomes so slow as to become negligible and meaningless for any practical purpose.

 

[tiger15]

When the growth slows down to non detectable rate, it’s equivalent to no growth. Fish don’t shrink in size at old age, but some develop crooked back. Aging fish are less agile, eat less, and are more susceptible to diseases that cut short their life and max size. It’s easier to see max size of short live fish, but hard to see max size of long live fish because keeping them alive beyond 5 to 10 year has low probability due to accident catching up.

 

[dan518]

I know for a fact a haitiensis put on about 1/2 lbs between the age of 5 and 7. Same with a trimac around the same age. Eyeballing the fish in the tank i didn't notice the growth of the fish due to the length to weight curve that most fish have.
Saying they stop growing at 5 years old because you don't notice if they have got any longer by eyeballing them in a tank is wrong.
I have seen evidence that new World cichlids keep gaining weight well after there 5 years old. I haven't seen any evidence to say that at 5 years old they stop gaining weight.

 

[Zanzag]

Exactly! Growth isnt just length in a fish. Length may slow down its not even noticeable, but theres no real stop to mass gaining. Kinda why fishing records are done by weight...

 

[tiger15]

It’s not new world or old world cichlid. It’s just long live cichlid continue to grow for a long time. Frontosa from the old world can live between 20 to 30 year, so are some large cichlid from the new world such as Oscar and peacock bass. This is why you may be shocked to see immense size Frontosa and Oscar in public aquariums that you never see in home or LFS aquariums.

The reason anglers measure fish by weight, not by length, is because it is easier. Measuring the length of a live fish is hard because they don’t stay still, besides, fish length to height ratio varies with habitats. For instance, fish live in fast moving stream have more slender built than the same species in slow moving lake.

Yes, many fish gain in bulk more than length as they mature. But still, they will stop gaining either at some point, which can be 20 to 2 year depending on species. Some of the shortest living cichlid I have had are Victorian cichlid. They bloom early, stop growing by 2, lose vigor and begin to decline by 3. My current longest living cichlid is a Zaire Tembwe Frontosa, 7 year, still growing at unappreciable rate, and my former Burundi Front, 10 year, died in an accident of my fault. In comparison to my large CA (Vieja species )experience, Front grow much slower

 

[neutrino]

Gaining mass with age doesn't happen in all species. A properly cared for Aulonocara that reaches max length between two and three years does not/should not/cannot continue to gain mass all its life. If it did that would mean it was overfed, obese, a prime candidate for bloat and it died before its time.

Obviously, there are fish that can continue growing all their lives, whether in length, bulk, or both, where older individuals can get huge. I'm not challenging that-- I fished a lot living in Colorado for 10 yrs and caught a 24" brook trout once, half that would normally be above average. But this does not apply to all species. You can fish Lake Malawi all your life, you're not going to find a 5 pound lunker peacock cichlid, nor a 2 pounder, nor will you find one in some big tank somewhere. They reach a certain size and that's it; at 3 years they virtually stop growing, at ten yrs. they're not measurably longer, taller, or wider than at 5. If one does continuously gain weight beyond 3 yrs. you're overfeeding and shortening its lifespan.

 

[duanes]

This may have little to do with this "continuation to grow" discussion, but...
I believe optimum conditions to what a fish has evolved to live in, in nature, have very much to do with long term growth in general.
Back in the 60s, Cichla were accidentally released into Lake Gatun here in Panama, and record sizes here are only about "half" the size found in the soft mineral poor waters of South America.
Lake Gatun is highly alkaline and at times, reaches a pH of 9+.
These out of norm water parameters for the Cichla species may have important impact on growth, all other factors being similar.
These may also be factors for growth in aquariums, if one tries to keep a certain species in non-normal conditions, compared to fish kept in conditions that mimic its evolution, and natural habitat, (although it maybe not immediately obvious), there may be long term effects.
In aquariums in combination with high nitrate and other low water quality conditions these factors may be not even a tiny blip on an aquarists radar, but may be significant.

 

[LBDave]

From what I have read indeterminate growth can vary by species. Also, the growth hormones and growth inhibiting hormones are interesting, tied into the fishes genetic makeup.
Environment is also part of the equation. As far as anecdotal information, I was truly amazed at seeing increased growth rate due to water changes. Possibly the fishes system recognizes the improved environment and this is a hormonal effect? Is tank size also tied to this? I believe it is but just one of the factors. I have seen 12" oscars raised in a 75 gallon tank. So its more than tank size.

 

[dan518]

Gaining mass with age doesn't happen in all species. A properly cared for Aulonocara that reaches max length between two and three years does not/should not/cannot continue to gain mass all its life. If it did that would mean it was overfed, obese, a prime candidate for bloat and it died before its time.

Obviously, there are fish that can continue growing all their lives, whether in length, bulk, or both, where older individuals can get huge. I'm not challenging that-- I fished a lot living in Colorado for 10 yrs and caught a 24" brook trout once, half that would normally be above average. But this does not apply to all species. You can fish Lake Malawi all your life, you're not going to find a 5 pound lunker peacock cichlid, nor a 2 pounder, nor will you find one in some big tank somewhere. They reach a certain size and that's it; at 3 years they virtually stop growing, at ten yrs. they're not measurably longer, taller, or wider than at 5. If one does continuously gain weight beyond 3 yrs. you're overfeeding and shortening its lifespan.

If there putting on 1 to 2% in length from 3 to 10 years on average and maybe 5% in weight your not going to notice, unless your weighing the fish in question or measuring in mm. Most fish species have a average life expectancy and a average growth rate, therefore they will have a average max size.

 

[dan518]

From what I have read indeterminate growth can vary by species. Also, the growth hormones and growth inhibiting hormones are interesting, tied into the fishes genetic makeup.
Environment is also part of the equation. As far as anecdotal information, I was truly amazed at seeing increased growth rate due to water changes. Possibly the fishes system recognizes the improved environment and this is a hormonal effect? Is tank size also tied to this? I believe it is but just one of the factors. I have seen 12" oscars raised in a 75 gallon tank. So its more than tank size.

A 12 inch oscar I would consider small, certainly the wild strains can and have hit 16+ inch. I have seen 14 inch reds before.