I was watching discovery channel a while ago and that thing looks like one of those leech things that drinks blood from a fish's gills. they scrape the gills until they bleed and then gorge themselves on the blood. They find the gills because of the chemicals they release. Aparently our urine relieses the same kind of chemicals as fish gills so when you are in the amazon your not supposted to pee in the water or else these things will swim up your ..... yea.. and make their home there and scrach the inside until you bleed and, you get the idea.
So, was your texas in a tank possibly where there were plants or wild caught fish from the amazon?
I dunno i could just be stupid here.