We have a 29 gallon freshwater and it requires a LOT of maintaining.
I would not get one again. There are daily jobs, monthly jobs (filters, etc), routine weekly care (keepiig algae away, cleaning), regular water changes of 6-8 gallons at a time, keeping water balance in check and of course feeding the fish.
The fish are very pretty...you have to get fish who seem to get along, we had a lot of fighters and lost some due to fights. Petco has been very helpful to us but I will say it gets old with all the maintaining.
We've had our a couple of years.