They may be "just fish" but you do get attached. Our fish are outdoors in our goldfish pond. The pond was here when we bought our home 3 years ago and we knew nothing about caring for it and the fish. There were about 30 or so fish in it. The first winter all went well,but the net winter was quite a bit colder and we lost all the fish. DH was heartbroken.
We replaced the fish last summer and purchased a heater for the pond. We had a very old winter this year and all 8 survived. We did lose one, however,to Betty our cat. I will post a pic of our pond-if you zoom in you can see that there are Christmas lights all around the pond.This tells us if the circuit breaker "pops" for some reason and the heater goes off. Pond is not a large pond but looks even smaller in this pic....