There's unfortunately no such thing as a 'small' goldfish. Those are stunted goldfish whose lifespan and health are detrimentally impacted on by being kept in small tanks.
Most of the goldfish I have seen sold as feeders are commons/comets and these are supposed to grow up to a foot long. Even a fancy goldfish is too big for a 10 gallon tank.
Your glass catfish also get up to around 10cm so need something 20 gallons and up.
Did someone advise you to stock your 10 gallon this way? It just seems very hodge podge, as the stock you currently have aren't compatible with your tank size or their tankmates.