Folks my wife has her heart set on Fancy goldfish in our new (to us) 80 Hex. I still haven't given up trying to talk her out of them but need some info. First, to me mixing goldfish with plants is like ringing the dinner bell. Are there any that these critters don't like to eat or destroy (other than silk or plastic). Second, what type of substrate and preparation is necessary. Finally, what type and how much lighting would I need.

I'd appreciate any insight that you may be able to provide.

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Doc

Dr Hank's 200 gallon Reef Tank
http://www.aquariumforum.com/f46/drhanks-tank-3440.html

I tend to think of goldfish the same way as you. They love their veggies and don't respect your desire to decorate with plants. Some of the tougher plants do not appeal to them as much, such as the Anubias that most vegetarian fish will allow to grow. In a goldfish situation, I would probably plant them in pots with a rock cover over the potting mix to make them harder to dig up. Be careful to make sure that anubias get good water flow around their rhizomes or they will die on you though. That usually means planting them higher than most plants but large pebbles around the base should still allow water to circulate freely.

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Fishless cycling

You could get some driftwood in there and tie the anubias on with fishing line. Java fern would work for the same purpose. That way you don't have to worry about substrate and can just go with gravel, sand, or whatever you decide.

How deep is that tank? Usually .7 - 1.2wpg would be considered "low light" and okay for anubias, java ferns, moss, etc. but if it's exceptionally deep, more light might be required to keep the plants healthy.

Another option would be to put some fast growing plants in there for the goldfish to eat, like duckweed, anachris, or even hornwort and provide it enough light/nutreints to outgrow the goldfish appetite. In a tank like this you could also grow some potted amazon swords which goldfish don't generally like to eat. Unfortunately with goldfish it's always going to be a guessing game knowing which plants they will eat and which they will allow to grow.

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29 Gallon Planted
1 Angelfish; 2 German Blue Rams; 11 Rasbora Boraptensis; 3 Khuli Loaches, 1 BN Pleco

20 Gallon Planted
2 German Blue Rams; 5 Corydoras Paleatus; 4 Otocinclus Catfish; Amano Shrimp

5.5 Gallon
Betta, Some plants.