I am also trying to figure out which plants would be proper for pond use. Since I didn't officially know the answer to your question, I googled "calla lilies" and in the first paragraph it lists their preferred habitat as streams and ponds... Yay! Another "house plant" rescued :)!

Not sure about the poisonous situation though, if you keep fish. Most of the plants I've found to be adaptable to water growing are poisonous, so maybe someone with more experience could help with that "little" problem.

Calla lilies are poisonous. We lost many of our fish because we were not aware of this. As soon as we removed the pots of calla lilies, the fish stopped dying.

I put in some mint and Siberian iris a couple of years ago. I planted them in kitty litter and put the whole pot in the pond, with the water just barely covering the rim of the pot. I'm in Zone 5 and they've survived the past 2 winters and are thriving.

I just bought some watercress which is hardy to zone 5, but I'm trying it out to see if it'll survive in a pot in the pond over winter.

I have pink callas in both ponds and the fish are fine. Just mentioning it.

Actually there are two different kinds of Callas. One is a marginal water plant, the other requires drier conditions.

Aethiopica varieties (Aethiopica, Aethiopica Childsiana, Aethiopica Green Goddess) are bog plants, meaning they like a soggy soil, or an almost constantly wet area to grow in. The flowers are white or at maturity green. There are no colored versions yet.

Your pink callas are terrestrial.

Thanks
So would the Calla lilies do Okay in wet soil? It dosnt stay constantly wet but.it stays moist its just wet right now because.of all the rain. Anyway Its the only spot that I can give them that will get them full sun.

Thanks
So would the Calla lilies do Okay in wet soil? It dosnt stay constantly wet but.it stays moist its just wet right now because.of all the rain. Anyway Its the only spot that I can give them that will get them full sun.

The problem is that terrestrial callas are prone to a disease called Rot. The microbe that causes Rot is prevalent in soils that are lacking in calcium. Wet or constantly too moist soils are usually lacking in calcium. It takes a couple of years sometimes to correct the balance and get rid of the microbe.

The disease spreads unbelievably fast and is not curable. I have lost an entire planting of dozens of callas in hours of when the first signs showed up. Even digging up the still seemingly healthy plants did not save them. They began rotting even as I tried to dry them out. The big diagnostician at the University of Wisconsin, Madison told me it was a losing battle and I should dispose of the plants in the trash. (I ran into her at a Master Gardener's class) There is no treatment. Callas are not the only susceptible plants. They are just more susceptible than most.

They need well drained soil with sufficient bone meal or liquid calcium added.