We took out the fish - 12 survived the winter - and put them in temporary housing (see tin bucket in forefront). We also found 3 frogs - still sluggish so perhaps not actually awake from their winter nap!
Pumped out the water, removed all the rocks. Put in a new liner and and replaced all the rocks, re-filled and put the fish back in. It is a much easier job with 2 sharing the work! We were able to get the whole project done in a few hours.