In most cases a healthy fish will avoid being sucked up into any filter unless you have gone totally overboard with the size and GPH of your filter for the size of aquariums you have.
The only issue is usually from baby fry fish or filters that do not have the correct filter inlet protection.
Most modern filters have a protective measure on the end of the filter inlet pipe to prevent fish from being sucked up into the filter and being harmed or evenkilled.
Only by removing this will you put healthy fish in danger.
Any fish that are unwell, old, or very young are at risk of being sucked up into your aquarium filter. They are often weaker and less able to swim away from danger. And therefore are in more danger of being sucked up inside the filter.
It’s not always instant death or harmful for a fish to be sucked up inside an aquarium filter. I have rescued many a small fish from inside my canister filter from both Freshwater and Saltwater aquariums.
There are a number of thinsg you can do to prevent and reduce the risk of this happening.
- Place the inlet pipe behind rocks or plants
- Ensure the cap provided is attached to the pipe
- Purchase the correct size filter for your aquarium
- Remove Fry and Tiny fish into a holding tank or Fry Floating tank until bigger
- Reduce or control the GPH flow of your filter
Unfortunately, even after doing all this, there are times when fish do still get inside your filter and as long as you remove them quickly it’s not always life-threatening.
If you do remove any trapped fish look for signs of harm or damage to their body. This could lead to infection and diseases being introduced to your aquarium
If this happens make sure you take them out and isolate them in another aquarium quickly. If you do feel that your fish has sustained too much damage to survive. It maybe time to consider euthanasia.