Yes, you read that right. A group of hippopotamuseses may be called a bloat. Or a crash. I prefer to save the crash label for rhynos.
For the curious: Many English terms for animal collectives go back to the 15th and 16th centuries. One influential work in this regard is titled the Book of St. Albans (1486). In it was a list of “the compaynys of beestys and fowlys." The book seems to have been popular, offering language tidbits for gentlemen-hunters looking for the right word for beestys to drop while telling storyes at dinner partyes (I'm gust guessing here).
