what sort of pump is it?
is this on the tank with the trickle filter?
Most external filters can be kept alive by letting water flow through them. With an external canister filter, you put the outlet hose into a bucket and let the bucket fill up. Then put the outlet hose back in the tank and pour the bucket of water into the tank. This should be done every few hours.
With trickle filters you can scoop out the water from the sump and pour it into the tank. It will overflow down the drain pipes and flow through the filter materials.
If the filter is not going to be fixed for a few days, then take the filter materials out and clean them in a bucket of tank water, then put them in the tank and leave them there until the pump is fixed.
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Reducing or stop feeding for a few days will not harm the fish and will limit the ammonia produced in the tank, and this will help keep the water cleaner for longer. Monitor the ammonia and nitrite levels each day and do a water change if there is any.
Increasing the lighting on the tank can encourage the plants and algae to grow more and use more nutrients. When the pump is fixed you reduce the lighting times back to what they normally are.
If you have a spare air pump, get that going and have an airstone bubbling away in the tank to help circulate the water and keep oxygen levels high.