Here's a funny little study I conducted...

[64BitGuy]

I caught enough common, yellow, and peacock butterflies to take up all the space in my inventory and sold it. (I can't remember exactly how many of each kind I had.) It was a little over 2,000 bells...not great. I had an Angelfish in my house and I didn't really want it anymore, so, I sold it all by itself. 3,000 bells. Just one Angelfish sold for more than an entire inventory of butterflies. Has anyone else tried anything like that?

 

[Pietro:)100]

I haven't tried anything like that but it's quite interesting! I might do a little experiment like that in the future

 

[isebrilia]

yellow butterflies are only worth 90 bells and peacock butterflies are 200, while an angelfish (which is rare in the game) is worth 3,000! prices are determined by how rare they are. just thought you should know that! c:

 

[LyraVale]

Sometimes it's fun to do these experiments, so I don't want to kill it for you. But an easier thing in this instance, is to just look online and see how much each bug or fish is worth.

I really like using http://moridb.com/items/bugs/ and if you look around it tells you the price of all the other items, furniture, etc in the game.

Anyway, you'll find the most expensive fish are the sharks, and the most expensive bugs are the ones on the island (or in the summer in your town) like the golden stag and horned hercules which are both 12,000. If you want to make a lot of bells, filling up your basket with those on the island can get you around 200K from one trip.

 

[Shimmer]

I did a similar thing with fruits which is why I don't bother selling them anymore. They aren't worth as much compared to certain bugs and fish.

 

[Yoshisaur]

Yeah I like to see how much I can get for things verses other things. I do realize I can look online at the prices but there's SO many bugs and fish I can't keep track of how much each one is. I just know if I hardly ever catch it, it's probably worth more.

 

[Snazzapple]

I sold a whole inventory of shirts maybe and then sold a fossil if that counts as anything. Although it's quite obvious that one fossil will sell for more than a handful of things. The shirts came to 2,000 bells and the fossil sold for 9,999 (market space) so there's something to think about.