Better than waterchanges would be a constant supply of freshwater. A small tank can be run with a dripping faucet and an overflow. A larger tank would need a faster supply of incoming water. I've seen astounding growth, However I question a fish's immune system when they have been kept in sterile environments. They become unacceptable to the slightest amount of ammonia and even Nitrite and Nitrates.
Combine Frequent water changes, with a low stocking density, and quality diet, in an oversized environement, and your fish will grow large, strong and healthy.
Combine Frequent water changes, with a low stocking density, and quality diet, in an oversized environement, and your fish will grow large, strong and healthy.