i have some in my outdoor pond right now and the fish are fine...ive put them in my fishtank before too and the fish seemed fine as well..if you plan on putting water hyacinths in a fish tank be sure to get a whole bunch of light on them of else they will die in a matter of a couple days or so
they grow in this beaver pond that is being mowed over for a new road and the local news paper said that they were harmful to aquatic life.now that i know that they r not ,im gonna go get some 4 my tank
On a macroscopic level they are harmful: Water hyacinths propagate extremely rapid under ideal conditions, blocking the water surface of ponds and preventing gas exchange and the uptake of sunlight. Thus, they can easily cause harm to local flora & fauna.
However, in a backyard pond or aquarium they are safe since you can throw out excess plants.
Again: Their blossoms are pretty, but in a tank you mostly see their roots. And they suck But check it out for yourself.