Backyard Aquaponics
A place to discuss aquaponics

With such a small system, if there is no bacterial colony established to break up the ammonia, two small fish can spike the levels very rapidly. Consider temporarily adding an activated carbon pouch into the waterstream to absorb some ammonia while the system catches up. No need for the filter system, just buy the pre-packed pouched carbon refill for a canister filter and rubber band it to the down spout or bubble stone. I keep some around for emergencies when i need to set up a hospital tank to keep the water safe temporarily. Just an idea if the fish start showing stress from the ammonia ( red streaks in fins, scratching/striking like their itchy, exc.)