Originally Posted by Blackfeet
No, that is good. It is a small tank so small fish of one species is usually best. Or one medium sized fish (meaning a fish that will grow to no more than 3 inches) like a male betta with a couple female betta or guarmis these fish do well by themselves but can be bred in a small tank to themselves. The rule is one inch of full grown fish per gallon so you can have 10" of fish. Make sure you are taking their full grown size into acount
I just wanted to point out that male and female bettas should never be kept together unless breeding, they will kill each other 99.9% of the time. You can keep female bettas together but its a lot of work and very specific requirements must be met.
Gouramis should never be kept with bettas as well since they are both anabantids and will squabble over the upper area of the tank.
The inch per gallon rule has mostly been discredited, its better to look at the needs of each specific fish and the bioloads they have rather than just the size. If I followed the inch per gallon rule, I could cram a 10 inch pleco in a 10 gallon which would most assuredly kill it.
I recommend that the OP check out the fish profiles tab at the top of the page and look at some of the profiles of the fish you are thinking about getting, itll help you out in deciding on what you want.
For guppies, stick with all males or all females or you will be over run with fry. These fish will give birth around once a month and to a lot of baby fish! Im still trying to clear them all out of my tanks e.e
As for puffers, they are notoriously picky eaters so please note that, they must have frozen or live food as flakes are nutritionally useless to them. They do need live snails as well though you do not need to worry about their teeth overgrowing since it doesnt seem to bother these specific puffers.
OP, id like to point you to this site which should help with your stocking, it will tell you when you are overstocked and the fish you choose will get too large for the tank you have in mind. Make sure you run your final stocking plans through the forum as we can help you fine tune them and make sure your fish are the happiest they can be c: AqAdvisor - Intelligent Freshwater Tropical Fish Aquarium Stocking Calculator and Aquarium Tank/Filter Advisor