How long does what last? The tank lasts as long as it isn't cracked, The filter lasts as long as it is cleaned, and you must do efficient research on the specific fish you have in mind for its lifespan. And by the way, this site doesn't count as efficient research.
Goldfish? That depends on the size of the tank. Let me start of by saying goldfish will stunt their growth in a tank that's too small. And for a straight bodied, 1+foot long Carp, almost all tanks are too small. What I'm about to say isn't officially written anywhere, but this will help you out best. All Common, Comet, and Shabunkin Goldfish should be kept in, at least, 5 foot deep, 20 foot wide pond(for them to live to their longest, of course.). Or, an 55+ Gallon aquarium(For one only). Pet store clerks don't tell people these things. Who would pass up the chance to buy a 33 cent 2 inch fish right?
4
39 mins
100 years
otto cats are your best pick as long as your other fish are not aggresive
1 min
Betta fish, guppies, tetras.
There are several fresh water fish that are 10 inches long, trout is a good example.
Probably as long as any other lean fresh fish. You should use it within 2 to 3 days.
I will only keep fresh fish (any kind) in the fridge 2 days.
Salt water fish should not be kept in fresh water. I dont how long they will survive but you shouldnt keep them in fresh water at all. If you have an emergency and you need to put them in fresh water, try to keep them in there for as short of a time as possible
The Arctic grayling.
That depends entirely upon its genetic code and the environment it is in.