Singular freshwater puffer in 20 gallon

I was thinking of doing a 14 gallon cube with 3 (or more?) pea puffers if that would work but was also wondering about doing a 20 gallon long with a singular puffer in it. Are there any purely freshwater species larger than an inch that I could keep alone in a planted tank? I was leaning towards a figure 8 until I learned they were brackish so if there’s anything like that out there that’s purely freshwater and not too difficult that’s what I’m looking for. Thanks!

 

I keep my Figure 8 Puffer (Puffy) alone in a 20 gallon brackish planted tank. I grow Anacharis in the tank. Anacharis is fine in brackish water. It grows floating, or stuck in the substrate. You remove the buried plant, clip off the tops, and replant the tops, discarding the bottom. This keeps the plant fast growing which benefits the tank. Anacharis is immortal!

 

I keep my Figure 8 Puffer (Puffy) alone in a 20 gallon brackish planted tank. I grow Anacharis in the tank. Anacharis is fine in brackish water. It grows floating, or stuck in the substrate. You remove the buried plant, clip off the tops, and replant the tops, discarding the bottom. This keeps the plant fast growing which benefits the tank. Anacharis is immortal!

How hard would you say it is to maintain the brackish water and conditions? Could I just use saltwater from a bucket (for fish obviously)? Also any other hardy plants that can work in brackish water? Thanks!

 

I change 50% of Puffy's water and add 1/2 cup of instant ocean. I just scoop the salt into the filter.

Brackish is very simple.

The hard part is the pH is high, so if you have any ammonia it will be deadly. (ammonia is more deadly at high pH). The tank needs to be fully cycled. But after that it is a piece of cake!

 

I change 50% of Puffy's water and add 1/2 cup of instant ocean. I just scoop the salt into the filter.

Brackish is very simple.

The hard part is the pH is high, so if you have any ammonia it will be deadly. (ammonia is more deadly at high pH). The tank needs to be fully cycled. But after that it is a piece of cake

I’ve read that they can be in freshwater too is tha true? If brackish has advantages over fresh I’d do that anyway just there is conflicting info