Well, science isn't always "nice" to the animals they work with, but knowing more about them always helps the ones we are "nice" to.
Sorry, I study environmental science, and we went spent some time in Duke marine labs to get some samples. We had to kill a lot of fish. But, as long as you know what you're doing, you don't even have to kill the fish or even make them taht uncomfortable to take a picture like these. You just anesthetize them, keep them moist, and get the pic. Lots of biologists do it, I'm sure breeders could too.