How Can We Know?

[Dorri]

How can I know the age of a fish when I buy it? Aprox how old are fish at the time of being sold in the stores? When a fish dies, I normally count from the time I purchased it, but really, how do I know how long my fish was in that store or elsewhere before it ended up in my hands? I plan on getting another fish, but would like to feel reassured that it is a young fish, so i don't lose it a few months down the road. I seen quite a large goldfish in the Store Aquarium and know just by looking at it, it took time for it to get that big. Any suggestions would be appreciated.

 

[rdd1952]

Most tropicals are juveniles. They are mostly all tank bred and shipped out as soon as they are big enough. The ones that are wild caught are shipped out as soon as they are caught and distributed shortly thereafter. I would think most of the fish you buy are less than 3 or 4 months old but I certainly don't have the data to back that up. Someone maybe can supply information to prove or disprove that.

As you mentioned about the goldfish, if they are larger than what you would consider to be "small" then they my have some age on them. Goldfish can live to be close to 50 years old in the right conditions though so even if you buy a large one, if you give him the proper size tank and proper care, you could easily have him around for 20+ years.

 

[Bignose]

Cut it open and count the rings? Oh, riiiiight, fish are not trees.

Well, if you are exceptionally experienced, a fish's age is directly correlated with its size. Fish do grow continuously their entire lives. Obviously, the growth rate over time is not constant, rapid growth when young and diminishing to almost zero when older. So, if you have a keen eye and know what size a fish is when it is a certian age, a guess could be made. That said, it really is only a guess because one can only know the average size of a fish compared to its age. Just like people, some fish are big, some are small, some are tall, some are short, etc. And, unless there is some other obvious determining factor (like a color change at maturity), there is no wya to know if you got an older shorter fish, or an average fish, or a young tall fish.

rdd is right in that the tank-bred fish are usually pretty young, the less time the breeder has to keep them, the less money it costs to keep them, so those fish are sent out as young as possible. But, wild caught fish could be anywhere from juvenille to exceptionally elderly. If you really want to know, this is where research comes in to play. You would need to research whether a fish is tank-bred or wild-caught or possible both. Then, research what their lifespan is like and be able to make a guess from there.

 

[rdd1952]

You're right about the wild caught fish and thanks for correcting me. I'm sure they are shipped out immediately but they most likely don't sort them and throw the big ones back. Even those can be judged somewhat by appearance though. If they are close to full size then they are probably older. That's where the reasearch comes in again. If you know how big they will be when grown, you can better judge how old they may be.