LOL, for a real culture NO FISH!!!
Even one would graze on them all day. As far as the HOB goes you would need a small pore size sponge or filter over the intake tube to ensure the pods would not get sucked up and blended. Feeding only requires a light tinting of the water a minimum of once per day. If you remember and have the time tinting the water twice a day would be more benificial and lead to faster and more dense population growth.