Entirely depends on the fish.
Some fish are not designed/evolved for strong currents and others are. If you put a fragile/docile/weak-by-nature fish in a strong current, you will kill it.
Likewise, when you talk about water flow, you have to consider how the flow is disbursed. 1000 GPH from a Vortech MP-40 in a 60 gallon tank is entirely different from 1000 GPH delivered by a concentrated powerhead which would likely blast rocks off of their piles...