best native fish to eat excess pond plants?

[birdbrain]

I live in northern ireland and would like to know if there are any native fish that would "hoover up" the excess pond weed we have growing in a very large pond.
It is about 50 metres in diameter at it's widest pioint.
The weed is covering 2/3 of the pond. It is growing from the bottom but I haven't been able to identify it yet.
I am basically looking for the aquatic version of a goat in the garden to keep the weed in check.
It is too large and has very soft margins making it difficult to get in to control the weed manually.

Thanks.

[Gill Catton]

hmmm trouble is with fish is that they can increase the nutriant load within the water - which can cause the growth of more plants - particularly algae.....
What is it that makes you think the weed is too much, do you need it for boating or something? - Ponds thick with weed can be very good for wildlife as it provides lots of places for invertebrates and amphibians offspring to hide or lay their eggs.
It would be interesting to know what the weed was perhaps its one of the non-native invasive ones that cause so much trouble?

[birdbrain]

Thanks Gill. I don't think its an alien one. It looks like a "poor man's elodea" - thinner, paler especially towards roots, fewer leaves, smaller leaves, not curled. The pond gets almost completely covered by it by the end of the summer. It looks like a very flat field by August - not nice to look at. I thought it would be better if something could eat it and keep some space clear. And perhaps we could catch some of the fish to keep the numbers down every year?

[serendipity]

Grass carp were and are often used for this purpose! They grow big mind, but you have a large pond. They taste good too according to Hugh Fearnley-Whittingmewhatsit!

[Dogghound]

Grass carp are native to Asia, there are no british species that actively eat vegetation im afraid and as Gill says fish could make the problem worse.

[serendipity]

2/3s covered how much worse can it get ? could always turn it into a car park !

[Dogghound]

Well for a start the whole pond could be coverd, then fish would add more nitrates to the water as well as reduce oxygen levels, they would then eat most invertebrates and amphibians as well as their larva. Then you would end up with nothing at all in the pond. So it could get worse.

[Pogo]

Originally Posted by Dogghound

..there are no british species that actively eat vegetation

Really, all native species of fish are herbivors?????

Originally Posted by Dogghound

Then you would end up with nothing at all in the pond. So it could get worse.

Wouldn't the eco system find it's own level again, the idea of a thousand fish fighting over one equatic incesct is one that interests me, please expand your theory?

[Pogo]

Originally Posted by Pogo

Really, * all * native species of fish are herbivors?????

I meant * no * native species of fish are herbivors, not all !!

I have some native rudd in a pond, and they definitely graze on the weed.

[Dogghound]

Rudd eat the occasionally bit of pond weed but dont actively eat weed alone, as you can see from the basic anatomy of a rudd the upturned mouth etc it its adapted for surface feeding on insects where it eats most of its food, not plants, so something that depends on aquatic vegetation for around 5% of its diet isnt going to make much difference. If you want to get technical roach, carp (although not native) and bream eat vegetation too (amoungst other species) but in such small amounts they are a worthless control hence the use of the word actively.

Second yes in the long run the pond will reach an equilibrium but if thats the way you want to go then whats the point in getting rid of the weed in the first place? If you want to wipe out all the pond life until the fish decrease in numbers then you really arnt bothered about the pond or its nature. The fish will upset the balance and eventually you will get a stunted population of fish in the pond that will eat away alot of the life and still have the weed problem. But hay you want me to expand my theory so there you are, if you dont understand this or want me to expand in alittle more detail just ask. In the mean time since you clearly know everything why dont you come up with a suggestion for biological weed control instead of trying to pick my positive reply to pieces, by suggesting rudd would control weed growth your clearly need to have a rethink.