Without weekly water changes for fresh water (monthly for salt water fish) chances of problems greatly increase. Fresh water changes, not only adding to evaporated water, will help your fish grow better and remove unwanted decaying matter from hidden areas. We recommend gravel vacuuming weekly to remove negative anaerobic bacteria from the substrate. These small toxic bubbles can release bacteria into the water and cause health problems for your fish. Water changes also decrease the speed at which nitrate levels rise.
Doing visual inspections of your fish daily as you feed them will make you aware of any differences that present themselves. This way if treatment needs to be started or you are aware of an approaching dilemna it can be dealt with promptly. Sometimes it's just a matter of doing some healthy water changes to get a fraying tail on the mend.
When adding new fish we all can encounter problems. One of my biggest issues is the gill fluke. I have had the best results with "Copper" products. Ionic copper such as Cupramine is my absolute favorite these days. It's much safer and more expensive than chelated copper such as Coppersafe, but harder to find. Gill flukes are nasty and invisible to the naked eye and retailers probably don't know they are present until obvious signs appear such as rapid breathing, scratching, and often skinny bodies.
Copper Safe can be harmful to some fish and plants so read package directions carefully and keep an eye on your fishes' behaviors.
If you have any problems that you need help with please contact me and I will try to assist you with solutions.