How big do fish really get?

I've noticed over the years that fish size (max mature size) varies depending on the source of information. Like a lot of information in the hobby, it's always stated as fact.

Example: Today someone posted that Peacock Gudgeons get to 3". My mature PGs are 2". The breeder I bought them from says they will max out at 2". Looking further online I found that they will supposedly grow to 1-2.5", 1.5"-2", 1-3", 2-3", 2, and 3". Also females at 2" and males at 3". My mature males and females are the same size. Seriously Fishy says 3". Fishbase says 3", Badman says 2-3"

Does anyone here have 3" peacock Gudgeons? I would love it if mine were that big. Are your males bigger than females?

Thoughts: 1)The high numbers may represent wild size, which may not be achieved in captivity....

2)Food quality and amount may limit growth...

3)Tank size can stunt them if too small...

etc.

My PGs live in a 29g. Would they be bigger in a 60g?

I'm just throwing this out there to see what others think or know.

 

water quality, tank size and food. Most of the info on the web is copied from one another. I suspect 3" is typical of quality advanced keepers.

 

Can you expand on what you mean by water quality and which qualities are most important? Do you mean the quality of the source water?

I've also noticed that my Bickford's Pencilfish that live in the same tank are bigger than what is stated as "normal" size. The breeder said that they would max out at 1.5" and they are over 2". They are bigger than the PGs.

 

there's just more to it, there's also genetics involved. You have to start with large examples of the species, and the first spawn will have some fast growers that grow large, and those again need to be bred together, so more of the spawn is of a larger size, at some point you have to outcross with foreign genetics or it will effect the spawning success rates, your outcross you'd want also to use an unrelated fish with attributes you want to solidify.
instead of color or pattern, you would be breeding to solidify the size genetics.

there's all the environmental factors as well, water quality, nutrition, space, but genetics is the big deal. Small starting fish, average common for the species, will produce the same, there might be an aberration of an individual that exceeds expectations, or something unexpected pops up, but it's very few and far between .

Like with chickens prior to 1910-1920, there were just chickens, they laid eggs, when they stopped, you cooked them. from that point on, the meat industry selected chickens to breed that produced lots of eggs and started early, and selected chickens that didn't lay many eggs but put on size and got big. this is how we got, the egg chickens that are smaller, and the monster broiler chickens, or meat chickens that hardly lay eggs.

Genetics is a huge factor, the capability of the candidate, and then selective breeding for the desired traits. the environmental factors being maintained as optimal just ensures the fish can reach it's full genetic potential. low nutrition, bad water, limited space, like you or me, this would limit us reaching our full potential also, just as low nutrition, bad air, or living in too small a small space from birth would, the main factor though to what our full potential is would be our parents genetics though.

the size of 3" for PGs I would assume is not the average size, but the max possible size observed for males and females maxing out smaller. Genetically superior sized examples would need to be selected for breeding stock, then maintain the environmental factors so the offspring can reach their full potential. and inbreeding, interbreeding and outcrossing, I think in the wild, this is bound to happen randomly with the variety of genetics in the wild, maybe even the random chance of a fish that exceeds 3" size. In captivity, I find it hard to believe most breeders really care about breeding superior sized examples and are perfectly happy cranking out average sized fish and collecting their loot for the effort, and not trying to make a line of max size PGs,,,, or looking to breed them to make them even larger than the max sizes through selective breeding.

 

Saw the same post and thought...that would be cool if my peacock gudgeon got to 3". My male is healthy, fully grown and definitely not 3". It eats great, isn't bullied, has awesome colors. I'm going to get 1-2 more so we'll see what those end up looking like.

 

Thoughts: 1)The high numbers may represent wild size, which may not be achieved in captivity....

Exactly the opposite. Usually captive specimens grow larger than wild ones.

3)Tank size can stunt them if too small...

Not really.

2)Food quality and amount may limit growth...

That's the closest you've come to the facts.

As the others said, it's a multifactor thing.

But if we only go by what info you can find out there what people write how big fish can get... Many sources have copied other sources and ultimately I'd stick to the scientific descriptions and sources that quoted those.
And as always: If a website wants to sell you something, maybe even the fish - Take their infor with a heaped tablespoon of salt.

 

I've known a couple of hobbyists who consistently grow fish beyond the commonly presumed maximum, including Peacock Gudgeons in excess of 3 inches. Many decades ago, it was rare for aquarium raised fish to match wild fish for size. As our knowledge of water systems has grown, so have the fish, so that we now tend to raise them larger than the average wild fish.

Genetics is one of the least important factors, though the occasional bad genetics cannot be ignored. Feeding is quite important, but this must be combined with water quality. NOT water chemistry (pH, DH, etc.), which is another minor factor that can be critical for some species. The quality, that is, the "cleanliness" of the water, the regular removal of pollutants via water changes, this is the second major key to raising large specimens. Heavy feeding is not good if you don't control the waste production. Space can help get more size on a fish, though the lack of it can be overcome with a lot of water changes.

The one factor that many usually miss is age/timing. Young fish grow faster than sexually mature individuals, and very young fry grow the most, so it helps to keep them surrounded by food, preferably live. Growth is more often stunted by insufficient feeding than by tank space. Growth slows tremendously when the fish reach sexual maturity, and the more growth you get before that point, the larger they can potentially grow.

So, as generally stated, multiple factors affect the growth of our fish. Some are a little more important than others, but all must be taken into consideration.

 

I have always reviewed those specs as "planning numbers" whenever I do research on a fish, I setup the stock list using the largest estimated growth size that I can find. It is my experience that all of the factors explained above play a roll in determining the final "size" of a fish. From food availability, water temperature, stress, and almost unlimited variables that we wouldn't normally consider.

 

A lot of fish can become bigger than most kept in fishtanks. There are a lot of sites on the internet that will give you a size that they will reach on an average basis. For in the wild most fish become bigger than the sizes mentioned on sites.

 

A lot of fish can become bigger than most kept in fishtanks. There are a lot of sites on the internet that will give you a size that they will reach on an average basis. For in the wild most fish become bigger than the sizes mentioned on sites.

That may be true in some cases but almost certainly not in most. Just as a couple of random examples that cross my mind, if you look up the size of Cryptoheros spilurus, usually 12cm is given. I measured a lot of these in Belize many years ago, the biggest sexually mature individuals were 7.26cm (males) and 5.05cm (females) - OK these are SL (standard length, not including the caudal fin), but even so, they are considerably smaller in the wild.

Seriously Fish says the largest officially recorded specimen of Laetacara araguaiae measured 34.9 mm. Mine are much bigger than that, even the females.

Food availably undoubtedly plays a role and also factors such as parasitism and predation in the wild that will result in most individuals not living to reach their potential size.

 

Seriously Fish says the largest officially recorded specimen of Laetacara araguaiae measured 34.9 mm. Mine are much bigger than that, even the females.

Same with my Dicrossus. The scientific description says 3.5cm. My wild bred (but tank-raised by me) ones reached end total lengths of 10-12cm. The wild caught adults I recently saw at the store were the size I got my fish as juveniles but fully developed.

 

Thanks everyone for the thoughtful answers and good information.