If you are finding too much food is reaching the bottom before the fish have chance to eat it, try adding a little at a time rather than feeding it all at once.
I am new to fishkeeping and I recently tried a food claimed to feed fish at different levels in the aquarium. When I added it most of it went straight down to the bottom of the tank due to the flow of the water. Is there a way to stop it sinking so quickly? Is it better if I turn my filter off when I feed the fish?
G. REES, EMAIL
It really depends on what type of filter you have and how you position it.
Most internal filters return water to the tank horizontally, which should produce a flow across the tank, (and often weakly back again toward the filter as the flow deflects off the opposite side). This should mean that any sinking food added will remain suspended in the water column for a short time as it sinks.
External filters generally have a similar effect but are more adjustable, so it is possible to position the return pipe or spray bar to send the water straight down to the tank floor, and this would rapidly wash any food down with it.
Some tanks have filters that are situated in the hood and work by gravity with the water dropping through them and then back into the tank; these can make a fierce downward flow as well. If your filter is pushing water downwards then it can be a good idea to switch the filter off during feeding to prevent this — just be sure to switch it on again afterwards!
Many fish foods have a mixture of densities in the one pack, so some will float, some sink rapidly and some slowly. In theory this should offer most types of fish a chance to feed. It might also be worth considering feeding in smaller quantities so the fish can gobble up most of the food before it reaches the bottom.
Of course any bottom feeding species such as Corydoras will appreciate the food that sinks to the substrate.
BOB MEHEN