In ordering Blowfish, is one being reckless to a morally unacceptable degree?
I don’t know if I would go so far as to say the term “reckless”, but probably the best word I would use would be “inadvisable”.
Blowfish are not kosher, which is the first warning sign. (If the Creator banned blowfish for the children of Israel, there is probably a good reason.) A kosher fish is a fish with both scales and fins (but only certain kinds of scales). Some fish that are not kosher are fish without scales or fins — such as blowfish, dolphin, and eels. Bottom-feeding fish are also non-kosher.
The laws of kashrut (kosher) are fascinating. They are pretty straightforward, and there are many health benefits to following a kosher diet. While I wouldn’t go so far as to say that eating non-kosher fish is sinful, it certainly doesn’t hurt to avoid non-kosher food, if only for health reasons alone.