Red onion snail, also known as the red-rimmed melania, is a freshwater snail that is native to Southeast Asia. It has a distinctive reddish-brown shell with a white rim and can grow up to 1 inch in length. 

The ideal pH level for a red onion snail is between 7.0 to 8.0, and the water temperature should be maintained between 75 to 82 degrees Fahrenheit. They prefer slightly alkaline water conditions and require a well-established aquarium with stable water parameters. 

In terms of care, red onion snails are relatively low-maintenance and can help keep the aquarium clean by feeding on algae and other debris. They can be kept in small groups, but it's important to ensure that the aquarium has enough space and hiding spots for each snail. They do not require any specific diet and can feed on algae, leftover fish food, and vegetable matter. Regular water changes and maintenance are also essential to keep the aquarium healthy and reduce stress levels for the snails. It's worth noting that red onion snails may lay eggs in freshwater aquariums, but the eggs typically take several weeks to hatch.