Hi and welcome to the forum. How big is your tank and how long has it been run? I don't know about a bottle nose pleco, but the peacock eel is a pretty big fish, and the 3 spot gouramis can be quite aggressive, so that will limit your choices.
The best point to start is what is type of water do you have:
pH
General Hardness
Carbonate Hardness
Then determine your tank size and shape, some fish have different requirements for tank shape and size.
Then select your fish based on how well you can meet their requirements and the type of aquarium you want to develop.
Don't forget plants. Plants actually make life a lot easier because they can process some of the nitrogenous compounds that the fish produce from their waste.
If you don't already know about the nitrogen cycle I would start here:
https://www.fishforums.net/threads/cycle-your-tank-a-complete-guide-for-beginners.475055/
There are three general groups of fish in regards to water. Fish that like soft acid water, fish that like neutral water with some hardness, and alkaline water fish that like harder water. It is easiest if you start with fish that are suited for the water you can obtain, and with the fish you have you will likely end up with at least a 55 gallon tank.
Your eel appears to be in the middle group, the Bottle Nose Pleco is likely more of an acidic softwater fish (there can be some overlap)(I am assuming you are talking about the Bristle nose pleco).
Serious Fish is a good site for some information but can be difficult to use.
https://seriouslyfish.com/?msclkid=4d2e00fad00911ec9b2dc9518d80319e
I find animal world ok for some fish as well.
https://animal-world.com/encyclo/fresh/fresh.htm
Take any advice from a LFS with a grain of salt. I learned the hard way about 3 spot gouramis. They are not a community fish in my opinion.
Good luck
