You don't need live rock for a fish only. The live rock is used for the anoxic areas and the beneficial denitrifieing this produces. The lack of an anoxic area will cause the excesive build up of nitrates. This is removed with water changes. The other pitfalls of high nitrates are algae growth. Marine fish are more sensitive to nitrate levels so they must be monitored.
This is assuming you use some sort of canister with sponges or wet/dry bio balls ect. Need surface area for nitrifying bacteria. Depending on the bio load, even the sand/gravel can be enough area. Usually fish only tanks are heavily loaded so count on weekly water changes with no rock.
|