For positive values, there will be some time t where the quadratic overtakes the linear which overtakes the constant. The best advice for dealing with infinity, though, is “don’t”. In some cases, you can deal with the approach to infinity as something else increases, but most of the time you don’t even need to do that.
Also, there is some point in time at which fish don’t help you. You only need to calculate to that point. And there is likely some sense in which earlier fish are more useful than later fish, and you should discount far-future fish to the point they don’t affect your decisions.
For positive values, there will be some time t where the quadratic overtakes the linear which overtakes the constant. The best advice for dealing with infinity, though, is “don’t”. In some cases, you can deal with the approach to infinity as something else increases, but most of the time you don’t even need to do that.
Also, there is some point in time at which fish don’t help you. You only need to calculate to that point. And there is likely some sense in which earlier fish are more useful than later fish, and you should discount far-future fish to the point they don’t affect your decisions.