How to tell how old your fish is???

[Magnum Man]

Age of fish has been talked about a bit lately, and it’s hard enough, trying to remember how long you’ve had a long lived fish…

But how old are they, when we get them is another question… typically if they are adult sized, can we assume another year, at least on tank raised fish??? Most of what I seem to be getting the last couple years has been Juvenal fish, but some, in particular wild caught Hillstream’s, and other odd fish, have come in adult size… I would suspect most are younger ( just as they may be easier to catch, and any with spectacular colors, like would be witnessed on breeding adults, would likely be picked over before they end up at my end of retail ) yet, odd balls like Sid ( my giant Oto ) are bigger than any of the on line data says they get, so aging a fish like that might be more challenging… I’ve had him / her 6 months, but aging a fish like that one is anyone’s guess… I’ve gotten several Hillstream’s, and African tetras, that have been wild caught, and came to me at adult size…

 

[Magnum Man]

Often we see embattled fish in commercial aquariums, that you can tell have lots of life experience, like the one @gwand posted recently, but often in private aquariums they may have lived a more sheltered life, and wear less battle scars of life, making it harder to age them

 

[Colin_T]

Captive and wild caught fishes can be adult size in a few months depending on the species, how much food it gets and how much room it has to grow. I have seen 6 month old rainbowfish that were an inch long and I have had 3 month old rainbowfish that were 3 inches long and breeding. Unfortunately there's no real way of telling how old a fish is unless you know when it hatched or was born.

 

[GaryE]

You have to figure a farmed fish is as old as it needs to be for colour, and not a day more. They don't make money cramming up ponds and tanks. So if you research a fish, you may find a comment on how old they colour up.
Wild caughts are what's caught. Sometimes you can tell by seasons. For example, cardinals spawn in December, in general. They go with the rainy season. If you get wild caughts in April, they're 3 or 4 months old. But if they're raised in Singapore or Indonesia, far from their natural range, that doesn't work.

 

[CassCats]

I always go that if, generally, the fish is not adult size, it's usually under a year old in cases of most small fish. Not usually able to get exact ages unless you or the breeder keep good records... but petstore fish are trickier as you aren't going to have those details. And wild caught is even harder to go by in majority of cases.


Larger fish is a different ball game and same goes with slow growing fish like plecos and many catfish. Even corydoras can take a long time to reach max size. In my experience, it's not typically until 18-24 months old for a corydoras of normal size to reach it's max size.

And then of course there's other factors, such as environment size, crowding, diet, and genetics that will play in on size and growth rate. Stunting can keep a fish undersized and then have it regrow later on when moved to better conditions. In cases like this you will have no idea the age. Unless the original owner/source knew.

 

[TwoTankAmin]

For most of the pleco species I have worked with I have a record of when I acquired them and their approximate size and if they are spawning for me or not. I have a single word file where I recorded all I could about when, from whom and if and when they began spawning. It included how many offspring at what size were available for sale.

I have sold off almost all of the breeders and offspring. However, I have one group left and just over 100 kids from them varying in size from wigglers in a cave to fish as big a s 3 inches. I also have the breeders, obviously. Here is the record I have for them:

L173 Wild Caught Group These will not be sold until 2023

I originally acquired this 10 fish group Oct. 8, 2015 almost all were at or close to a spawnable age/size. They came from somebody who imported fish and kept some for his own private collection, but did not spawn them. He sent me the fish and it was my job to spawn them. If I did so, we would split any fry 50/50. It took some time, but I did finally spawn them and eventually ended up buying them. I also got 6.5 of their half of the fry plus my 6.5. They are actively spawning at this time. Vid of them shot Sept. 2017 by Rachel:

Planetcatfish thread + pics https://www.planetcatfish.com/forum/viewtopic.php?f=5&t=42699

To date I have gotten many offspring. I personally sold 27 and then turned over sales to other people. They have sold or stolen* 70 and my current vendor has about 20 in stock. There are currently 55 +/- 5 offspring in my grow tanks. There are likely another 25 in the breeding tank.

All offspring above are for sale now

I have decided to hold onto the breeders until next year. They are my only group remaining. The above was last updated in early 2022. But, based on the fact that this fish is very slow growing, I can estimate they were between 4 and 5 years old when I acquired them.

 

[emeraldking]

How to tell how old your fish is???​

That's something quite hard to tell... There are more factors that you have to take in account. The conditions a fish is in may vary the stage of development for each individual fish. That may result in an incorrect estimate of the age. Unless you know when a fish was born, of course.

 

[Magnum Man]

Not sure if size is any real indicator… I got a small shoal of both Cory’s, and Panda Garra’s, that each came here tiny, at like 1/2 inch size, and both of those groups achieved full size in 3 months or less… they were in very different tanks, so no tank magic…

And I received a very non wild caught, blue eyed, albino, long fin, bushy nose, pleco, that arrived about half grown, and it doubled in size on 3 months… and at the same time, I got 3 large giant Oto’s that haven’t changed size at all in those 3 months…

It’s taken about a year and a half for my Tin Foils, to go from 2 inches to 9 inches