How determine age of fish?

[Rajesh]

If you plan to purchase fish, one need to know lifespan and age of the fish when you get it.

One may end up with fish, that die too soon and make you disheartened.
size may not go hand in hand with age.

 

[Meyer Jordan]

It is practically impossible to determine the age of a fish in other than the most general of terms without knowing the general time of birth due to differences in genetics, past feeding regimes, and ambient climate history.

 

[MitchM]

Fish can live for years or decades, make sure whatever fish you obtain come from a healthy environment and you keep them in a healthy environment for the future.
Fish that are raised in heavily medicated environments or are not acclimated properly tend not to survive for very long.

 

[CometKeith]

Rajesh. Have you had this problem? I have been keeping a fish pond about 9 years and never have had a fish die of old age yet. My oldest fish is about 8 years old. Just curious do you have an outdoor pond? I visited India a little over a year ago and I know it goes from almost no rain to too much rain other times. I would think that would be hard on a pond.

 

[Rajesh]

Rajesh. Have you had this problem? I have been keeping a fish pond about 9 years and never have had a fish die of old age yet. My oldest fish is about 8 years old. Just curious do you have an outdoor pond? I visited India a little over a year ago and I know it goes from almost no rain to too much rain other times. I would think that would be hard on a pond.

I have mollies (different color, bi color) tank (4ft ) open one with lily, I have to put pipe to set level water during rain season to drain excess water.

other smaller tank under partial shade:

Guppies (red tail)tanks with blue lilies ,
white mollies with lotus,
sailfin dalmatian mollies with bicolor streak lily

small aquarium 3 ft with two goldfish and one pleco with different aquatic plants, this one has been set up again recently.

you can see I have not kept fish that have life span more than 2 years, I used to add fish to aquarium but they always die on me.

Some fish that had died in the aquarium (small internal filter, heater and air pump) without plants, pebble as floor cover

2 fighter fish, without knowing they would rip each other to shred
6 black mollies, they lived long but eventually died
3 goldfish, they were swimming like crazy bumping into glass, later realized they had lice, purchased salt from store and medicines (drops), all were useless, I took the fish and remove lice with help of tweezers,
Gave up hope of keeping fancy fish, I went for danios they lived the longest, after they passed away leaving a lone survivor which I still have in a big bowl with plants.
I bought two shark along with pleco, that stupid store guy packed three of them together. after few days they got infected and died. Pleco has bony spike allover its body. Gave away the pleco to a friend.

Gave up keeping fish in aquarium, on the other hand fish in tank were doing fine.

In a way realized fish don't do well in aquarium without plants or I end up with wrong fish

Anyway, there was a thread about fishes in another forum, which stirred my curiosity to try again.