I think your best bet is to research large amounts of different fish if you might potentially get any new fish.
That way if a good deal on some rare fish comes up, you can make the impulse buy because you'd already be familiar with the basic care any fish they might get.
Also it might help because when I used to get fish many were not indenfied properly so it was basically the same as an impulse buy.
When I bought my synos who were intended to live in my 55 gal, I thought I was getting a smaller species. So before I bought them, I never researched syno. eupterus because I didn't know that's what they were.
That way if a good deal on some rare fish comes up, you can make the impulse buy because you'd already be familiar with the basic care any fish they might get.
Also it might help because when I used to get fish many were not indenfied properly so it was basically the same as an impulse buy.
When I bought my synos who were intended to live in my 55 gal, I thought I was getting a smaller species. So before I bought them, I never researched syno. eupterus because I didn't know that's what they were.