IMO no matter what you plan on housing you want a minimum of one pound per gallon. with less you stand a higher chance of ammonia spiking from feeding or any animal die off. even with a super light bioload, or rather especially with a super light bioload, as with a super low bioload your biological bacteria will be minimized due to lower nutrient availability, making it easier for your tank to expirience swings from just about any sudden increase.