Lifespan???

[JeffNebraska]

I have some Cardinal Tetras and some Bosemani Rainbows that are now approaching two years old. Some of the tetras are starting to look skinny and less vivacious. The Bosemanis appear to be at the prime of their lives.

I've never really gotten a straight answer as to the expected lifespan of freshwater fish under ideal tank conditions. What's the collected wisdom on that?

Should I blame myself for a couple of straggly looking Cardinals? I already do.

[TankGirl]

Since you really can't tell their age when you are talking about small tetras (you don't really know how old they were when you got them, most likely) it is very hard to predict how long a fish will live. I have a single cardinal tetra that is over three years old now, and he is the only cardinal in the 55gal community setup, so for a schooling fish like that it is certainly not ideal conditions, yet he soldiers on.

The rainbows should give you a few more years - you may have been able to tell that they were juveniles when you got them if you noticed growth after that, so you might have a better idea. I would assume that the rainbows would live a bit longer than the tetras, but skinny less vivacious tetras may be suffering from a disease - how is their color?

[poikilotherm]

It's pretty variable between species, and I have heard that Bosemani Rainbows can live over 4 years, and have heard 4-5 years for cardinals. The genetic stock quality of the fish is a huge factor IMHO, and unless you know the breeder, that's pretty hard to get a handle on.

[MarkLehr]

I can testify that Bosemani can live over 8 years.

[FishLover14]

Around 4-5 years for both maybe...

Dan