I wouldn't personally do either of those things. Clown loaches prefer to be in groups of at least three and will grow to a 1' each. Plus, your tank is fully stocked as it is.
As for the puffer, yes, there are fw puffers. But they are known fin nippers. Big time.
All you need to do is make sure not to overfeed. Without excess food there will be no excess snails. Some snails can be a good thing. They help clean algae and the excess food/poo that is to be expected.
If you do end up having a problem - which I don't foresee - just stick a piece of lettuce or zucchini in the tank when you go to bed. Then take it out when you wake up. That simple
As for the puffer, yes, there are fw puffers. But they are known fin nippers. Big time.
All you need to do is make sure not to overfeed. Without excess food there will be no excess snails. Some snails can be a good thing. They help clean algae and the excess food/poo that is to be expected.
If you do end up having a problem - which I don't foresee - just stick a piece of lettuce or zucchini in the tank when you go to bed. Then take it out when you wake up. That simple