Jose, sorry did not check the board yesterday.
If situation is holding as was yesterday, I'd head to Coral Reef or somewhere else that carries Chemi-Pure and run that. Better than carbon. In fact, I'd run that at Purigen. And I'd float them in bags in the tank with the fish, in high flow areas.
That in addition to water changes. You may never know if it was a spawning or the drain stuff. I find the drain thing unlikely, but who knows?
I'm not sure I'd go the massive water change route. Well, I'd do that first, then frequent (every few hrs) 10% changes if possible.
good luck.