I started with the aquarium hobby taking care of goldfish. When I saw what people were doing with planted tanks, I was determined to set up a planted goldfish tank. As I learned about plants, I realized the challenges that goldfish create. Goldfish create a lot of waste. Goldfish eat everything.
There is a lot of misinformation regarding fancy goldfish. Fancy goldfish require different care than the typical comet goldfish. They do better at temperatures around 74 degrees, unlike comets. They require about 10 gallons or more per fish, depending on their size. They can grow to the size of grapefruits and can live for 20 years.
From what I’ve read, fancy goldfish bother plants less than comets. If you feed the Fancy goldfish well, they can be trained to ignore certain plants. Since each goldfish has its own personality, you will have to experiment to see what works the best. Dealing with the high phosphates and nitrate requires the use of fast growing plants. The biggest help with this for me was Hygrophila polysperma. My setup was a high light, Co2 injected tank. I focused on growing the plants, so that even if I did have problems with algae, I would have so much growth by the end of the week that I could just replant the stems.
The tank did have problems with staghorn algae and black brush algae. At one point I tried using SAE to deal with the black brush algae. As long as you don’t have too many goldfish in the tank (I had 3 in a 45 gallon and it was hard to balance), and you keep the light, fertilizer and Co2 balanced, the tank will be successful. The tank needs to be heavily planted to deal with the waste. I eventually gave up because I wanted a smaller tank that was easier to deal with. I was replanting every two weeks compared to just trimming plants like you would in a tropical tank. I always wanted to do a tank with dwarf lilies, to look like you were looking under a pond. I also think lilies are appropriate with goldfish. Floating plants help a lot because you didn’t have to deal with algae, and they consumed a lot of the nitrate.
Floating plants are the easiest to use with goldfish. I never found a really good carpet plant to use, because goldfish like to dig up the substrate so much. I used the following plants in my setups.
Plenty more, experiment.
I had two small koi which I rescued from a natural spring in my backyard after it accidentally got drained during a construction project. When I realized I couldn't put other tropicals with them I decided to do plants which is what got me started in this hobby. Everyone's experience is different but my fish didn't eat the plants. They were always rooting around though and I had to often replant anything that was not established or planted deep in the substrate.I really want to add some plants to my goldfish tank. I've temporarily had to downsize tanks for them, so I need the plants to keep it balanced. Which low-light plants will they not eat? I was thinking a nice Java Fern and some Java Moss?