Do old fish differ from young fish?

[JBM]

The forum at Aquaria Central suggested I post a message here, given that loaches can live a very long time. I'm a journalist working on a story about aging in animals--there's lots out there about mammals but not much about fish. I thought I'd ask people who may have kept fish for a long time whether they see differences in the social role or behavior of older fishes versus younger fishes. Any thoughts or experiences, anyone?

[Jim Powers]

In my experience, the botias tend to become more reclusive as they age showing themselves much less than the young do.

[hx]

The forum at Aquaria Central suggested I post a message here, given that loaches can live a very long time. I'm a journalist working on a story about aging in animals--there's lots out there about mammals but not much about fish. I thought I'd ask people who may have kept fish for a long time whether they see differences in the social role or behavior of older fishes versus younger fishes. Any thoughts or experiences, anyone?

A big physiological difference in between mammals and fish is that the fish tend to grow throughout their lives. Social role within fish populations very often go hand in hand with the size of the fish.
Older fish = bigger fish = dominant fish.