Aquarium snails, bad or good?

I recently went to a pet store and while checking on the fish aquariums I noticed some cutie little snails in them that naturally made me wonder, why are they in there?

I always thought aquarium snails presence was harmful since they are plant predators, and plants are necessary to keep nitrogen in the right level to maintain water in good condition and provide enough oxygen to fish. Moreover, aquarium plants ensure the precise dose of CO2 and right lightning.

From this, you can naturally deduce that snails must be taken away immediately. However, NOT ALL snail species are harmful for an aquarium; in fact, they can be beneficial to keep it in good condition. Therefore, we have to learn how to tell good snail from bad snails.

How to indentify good aquarium snails from bad snails

1. Snail classification: identify which type of snails you have in your aquarium.
   
2. Holes in leaves: check if your aquarium plants have any holes.
   
3. Snails number: you know you have too many snails when the aquarium is visibly destroyed. You should proceed to remove them before they form a plague.
   
4. Snail shell: look if they have these characteristics:

1. 
   
   a) Oval shell: it is called Lymnaea stagnalis and is one of the most dangerous nails. It spends most the day devouring plants. Be careful, they reproduce themselves quite quickly.
   

• b) Swirl shell: easily confused with a conch, it is known as Malaysian trumpet snail. When you have just a few of them they do not represent any major danger, since they help cleanse and refresh the fish aquarium. When they grow in large numbers, they will need more plants and they will be hard to detect, since they spent most of the day under soil.