Is there a way to grow a fish to its max potential size in home aquariums?

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Firstly, totally unproven but I believe how a fish is handled as a fry can set the whole tone for its life. In the first year they will be growing more rapidly than ever again. Any growth lost from long shipments, stress, weaning of food, all comes off the top of the final max size at the end in my opinion.


I think this is most likely true of mammals and probably true of reptiles but fish might be the exception. I know there are a few papers on fish growth/stunting and I seem to recall reading something in that regard. It's not a subject that really interests me.

In summary large tank, water changes and varied diet.


I can think of a few more things but I'll keep them to myself just in case I participate in a grow out contest one day.
 
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Below is a repost of mine that demonstrates how different the optimum frequency of feeding can be among different species of fish.

Just keep in mind that how much one feeds, can be just as important as how often. Both how much and how often one should feed is a tricky question, dependant on the species of fish, their typical activity level, and even more important their life stage. I feed adults once a day, and skip feeding on water change days. So no more than 5-6 times a week. When I was actively breeding, fry and young juvies generally were fed 2-3 times a day due to having higher metabolic rates, so their feeding frequency was different than adults of the same species.



In a past discussion on "how often" one should feed I posted a few links to scientific papers that demonstrates how different the optimum frequency of feeding can be among different species of fish.
Most tropical species have yet to be studied for optimum nutrition vs growth, or for that matter anything. Long term studies for the vast majority of tropical species simply don't exist, but common sense and experience over the years dictate that clean unpolluted water with proper 02 levels, quality and correct quantity of nutrients, and an overall low stress environment is always the best avenue to maximize the genetics of any individual fish.





As far as feeding, it's a complicated subject. From a paper that I read a few years back...….



The initial observations in the present study did not detect further growth responses (on percent basis). In the present study the higher body weight was observed in fish fed to a frequency of two times per day. Similar results were observed by James and Sampath [26] in Red Swordtail (Xiphophorus helleri) which indicated that feeding twice a day resulted in the highest growth and reproductive success of this specie in a cultured system, when compared with 4 alternative feeding regimens (once, thrice, once and twice a day). James and Sampath [26] had similar findings in Siamese fighting fish (Betta splendens. Regan) who showed that fish fed twice a day to satiation elicited maximum growth and reproductive output when compared with its counterparts (1 meal in 3 d, 1 meal in 2 d, 1 meal/d, and 3 meals/d). Contrary to our results commercially cultured fish species such as Black Rockfish (Sebastes schlegeli) suggested that feeding to satiation once a day resulted in optimum growth [27]. Gibel Carp (Carrassius auratus gibelio), showed a significant surge in growth rate and feed efficiency when feeding frequency increased from 2 to 3, 4, 12, and 24 feedings per day, with the recommendation of 24 feeding times per day for this species [15]. The difference in results might be due to the fact that goldsh is not usually reared for commercial purpose. Moreover, this fact also leads to the fact that there is a need to improve the genetic potential of goldfish if we want to rear it for commercial reasons. In the present study, the maximum weight gain was observed in the feed (B) and the same result was observed in Siamese fighting fish (Betta splendens. Regan) which showed that 2 meals per day fed to satiation are sufficient to support the maximum growth. Further it has been reported that ornamental Red Swordtail (Xiphophorus helleri) fed 2 meals per day resulted in the greatest growth [28]. But contrary to present study the juvenile Atlantic Halibut (Hippoglossus hippoglossus) displayed improved growth rates when fed on satiation 5 times per day, compared with one time per day [29], and African Cafish (Clarias gariepinus) exhibited greater growth rates when fed to satiation twice compared with 3 times per day [30]. In the present study the better feed conversion ratio (FCR) was observed in Feed (A) but contrary to present study best FCR were observed for the Goldfish fed 4 times per day, indicating that this frequency of feeding was optimal, suggesting that both growth and feed utilization are more efficient at this feeding frequency [31].


PDF | Influence of Feeding Frequency on Growth performance and Body Indices of Goldfish (Carrassius auratus). Available from: https://www.researchgate.net/public...d_Body_Indices_of_Goldfish_Carrassius_auratus [accessed Jul 11 2018].
 
Many cichlids attain larger sizes in very well kept aquariums than they do in nature.
This is probably because in nature predation gets many before they have a chance to reach full potential.
And the larger a fish gets, the more obvious and desirable a food source it becomes, to predators like large birds and reptiles (like crocs), and man.
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Where I live, large cichlids are a staple item on the dinner table, below a Peacock bass fry.
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On the other hand, fish that live in small tanks, that get few water changes often achieve only stymied growth because of excess nitrate, and other nutrients in tank water.

In the Cenotes of Mexico I have seen many large JDs (10"+).
In these Cenotes with upwelling from underground springs provide constant 100% water changes, with no detectable nitrate.
The space in the smallest Cenotes are the thousands of gallons.
The Cenote in the video below was one of the smallest I dove in.
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Compare this to the average aquarium individuals where JDs max out at only @ 6" housed a 100 gallon tank (swimming in high nitrate 20ppm+(fish urine), that gets "maybe" a 40% water change once per week.
 
For the nit pickers ….

Nitrate is but a single measuremement, in the grand scheme of overall pollution.

Increased pollution, to which generally also means increased bacteria loads, can stunt growth, as well as cause an increase in illness.
 
You'll notice I said high nitrate in combination with other nutrients (nitrate being the obvious one we normally test for).(and I should add all the other stressors of captivity in a puddle)
As with many things, a modicum amount of one pollutant mixed up with even minisule amounts of others, sets up a toxic soup that leads to chronic (and growth inhibiting) conditions.
 
You'll notice I said high nitrate in combination with other nutrients (nitrate being the obvious one we normally test for).(and I should add all the other stressors of captivity in a puddle)
As with many things, a modicum amount of one pollutant mixed up with even minisule amounts of others, sets up a toxic soup that leads to chronic (and growth inhibiting) conditions.


Citation required.

Hit the edit button and delete "nitrate" from your post.
 
The study on salmonoids certainly does throw a spanner in the works towards nitrate. Was this nitrate then added via chemical means to elevate the levels? I am fairly sure that if nitrate levels rose to 443 ppm purely through organic pollution then it would not be a healthy environment at all. S squint are there any wider studies available, testing on more species of fish from different genera?
 
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The study on salmonoids certainly does throw a spanner in the works towards nitrate. Was this nitrate then added via chemical means to elevate the levels? I am fairly sure that if nitrate levels rose to 443 ppm purely through organic pollution then it would not be a healthy environment at all. S squint are there any wider studies available, testing on more species of fish from different genera?


There's an old, somewhat informal study where they simply stopped changing water at a catfish and bass farm for months and noted no difference in mortality or growth rate.

Most of the modern studies don't do that, preferring to only examine single variables.

This study used a "drip" system (3.7 L/min) then continuously dosed sodium nitrate in the "high nitrate" tanks and sodium sulfate in the "low nitrate" tanks to keep sodium levels and TDS/conductivity the same.

They also compared fin grading, mortality, and even blood work and found no difference.

Nearly all studies focus on aquaculture species. Well, Stendker discus says their nitrate levels are off the charts yet they produce world class fish.
 
There's an old, somewhat informal study where they simply stopped changing water at a catfish and bass farm for months and noted no difference in mortality or growth rate.

Most of the modern studies don't do that, preferring to only examine single variables.

This study used a "drip" system (3.7 L/min) then continuously dosed sodium nitrate in the "high nitrate" tanks and sodium sulfate in the "low nitrate" tanks to keep sodium levels and TDS/conductivity the same.

They also compared fin grading, mortality, and even blood work and found no difference.

Nearly all studies focus on aquaculture species. Well, Stendker discus says their nitrate levels are off the charts yet they produce world class fish.
Interesting. I am not dismissing the notion that Nitrate is something like a canary in the coalmine; the main observable, quantifiable pollutant in aquaria that indicates a buildup of waste that would otherwise cause most of the health issues encountered by fish in improperly maintained systems
 
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