Both my round tub and water fountain were too small for all the plants and the gold fish. We had moved them in bigger containers. One of the tubs can hold 220 litres and it is located in front of the front door. The other one is smaller (120 litres) and it is in the covered patio near the back door.
My husband built wooden frame around the bigger tub to protect the plastic from the sun in order to make it last longer and also to make it look nicer. I think the goldfishes are much happier now and I notice that they are getting bigger and bigger. I just hope that they will not multiply as we have no place to put them and too many fish will spoil the ecological balance.