I am fairly new at this hobby but quickly buying more and more! I have a 29 gallon tank with Bio wheel filter and 1 heater. I also have an undergravel filter
Regular water changes and don't over feed. Other than that, just look at your tank, look at your fish, you will see what you need to change if anything!
4 x Dwarf Gourami's
2 x Pacus
1 x Pleco
1 x African Chiclid
All fake plants
Go big or go home
Just got into this hobby about 3 months ago, started with a 10 gallon, now a 29 gallon, and buying a 90 gallon at the start of summer, check back for pics of that in the future!
When you see signs of stress in your fish, you can then take steps to identify the source of that stress and then to resolve it before it becomes a major issue.
If you're looking for a unique way to stock your new tank, give freshwater shrimp a try.
If your fish is suffering, you may want to consider euthanasia as an option to humanely end his pain.