Brave survivor

We have had several lots of goldfish, good for eating the insect lavae in the water feature.  But our cat and other neighbourhood moggies have used them as sport when not chasing birds.  Down to one again, think it is the same one from previous batch.  Yesterday water lily missing and when investigating found at bottom of pond, guessing knocked over by cat.  Then today the pump stopped working, clogged with soil from pot.  We rescued the remaining fish, changed the water, cleaned out the pump and put him back home.  Don't know how long he will last as the water is so clear now can see him at bottom of pool.  Trying to come up with a way to put a cover at surface level to protect it.