What type of freshwater or brackish water puffer can you put in a 10 gallon aquarium if the only fish is puffer?

It's not recommended to keep any pufferfish in a 10-gallon aquarium, even if it's the only fish. Here's why:

* Space Requirements: Most pufferfish species require significantly larger tanks than 10 gallons. Even the smallest species, like the Dwarf Puffer (Carinotetraodon travancoricus), need at least a 10-gallon tank per individual, and ideally more.

* Aggression: Many pufferfish are solitary and territorial, and they may become aggressive towards tankmates or even themselves if confined in small spaces.

* Water Quality: Pufferfish produce a lot of waste, which can quickly pollute a small tank. They require frequent water changes and filtration systems to maintain good water quality.

* Diet: Pufferfish have specialized diets that can be challenging to meet in a small tank. They often require live foods and specific types of invertebrates.

Instead of a 10-gallon tank, consider these options for keeping a single pufferfish:

* Dwarf Puffer (Carinotetraodon travancoricus): These tiny puffers can be kept in a 10-gallon tank, but only one individual.

* Larger Tanks: Most other pufferfish species require tanks significantly larger than 10 gallons. For example, the South American Puffer (Colomesus asellus) needs a 20-gallon tank, and the Red-Eyed Puffer (Tetraodon erythrophthalmus) needs a 55-gallon tank.

Before you decide on a specific pufferfish species, research their needs thoroughly. You'll need to understand their size, diet, temperament, and water parameters to ensure you provide a suitable environment for their well-being.

Remember, keeping a healthy and happy pufferfish requires careful planning and commitment to providing the right conditions.