It is not uncommon to be given the wrong information and not always the direct fault of the employees. The employees at a pet store do not all own pets, nor do all of them know a lot about pets. The person who sold you the
betta fish was probably selling you things marketed for betta fish in the store. It’s old, but there is still a misunderstanding out there that a male and female betta can be kept together (completely false).
This doesn’t mean you shouldn’t get advice at a petstore. I usually evaluate the care of fish at a petstore before I buy fish or ask for advice. If I see incompatible fish together, overstocked tanks, or lethargic fish, do not buy from there as their is a high-risk of getting a sick fish. With bettas it’s a little different as they are in cups. I would look at all the bettas. How many cups do they have, how many bettas are dead/ dying, do the cups look cleaned.
At the petsore, ask to speak with the person who manages the fish. This person is most likely to give you reliable information. It is good to ask this person about the fish as s/he knows the fish and may be able to tell you things about their temperament based on what s/he has observed. Generally, you can tell if a person knows their stuff, but I like to say a few things that I know about fish as a question or comment and see if s/he can correctly answer my question.
Still, it is important to always do your own research. Never solely rely on the advice of others. There are many hobbyists out there and many different opinions on fishkeeping. Some are outright false, and some depend on other factors. Know what you need to do and what your fish needs.
