hi everyone! i have had 2 goldfish (klaus and frannie), in a fully cycled 20 gallon tank for 6 months now. I will be moving to a bigger tank within the year, but in the meantime, the bigger fish (klaus) keeps sucking up and spitting pebbles out. i have thought he was choking on pebbles more than once and really want to get rid of them. had i more time to research i may have just gone bare bottom, or chosen sand instead of pebbles. it seems like a big undertaking and i am not even sure it would be a good idea to change or remove the substrate at this point. any and all advice is welcome, thank you in advance!