"The aquarium said it tried the treatment after struggling to eliminate the parasites, which were described as part of the Trematoda class of parasitic flatworms."
Looks like they tried some kind of flatworm treatment. The LA Times has more info on which specific internal flatworm they were dealing with.
http://www.kiiitv.com/story/28810355/major-fish-tank-disaster-at-texas-state-aquarium
http://www.nbcnews.com/news/us-news/parasite-treatment-kills-many-fish-texas-aquarium-n342461
http://www.latimes.com/nation/nationnow/la-na-nn-texas-state-aquarium-20150415-story.html
... and the reddit discussion if you want some TL;DR stuff:
http://www.reddit.com/r/ReefTank/comments/32ss35/texas_state_aquarium_suffers_accidental_massive/
Looks like they tried some kind of flatworm treatment. The LA Times has more info on which specific internal flatworm they were dealing with.
http://www.kiiitv.com/story/28810355/major-fish-tank-disaster-at-texas-state-aquarium
http://www.nbcnews.com/news/us-news/parasite-treatment-kills-many-fish-texas-aquarium-n342461
http://www.latimes.com/nation/nationnow/la-na-nn-texas-state-aquarium-20150415-story.html
... and the reddit discussion if you want some TL;DR stuff:
http://www.reddit.com/r/ReefTank/comments/32ss35/texas_state_aquarium_suffers_accidental_massive/