Duckweed in a Goldfish Tank

T

thebeasle

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Nov 12, 2012
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TL;DR: Any tips for keeping duckweed in a goldfish tank long term? How to adjust diet? I've had duckweed in a 75 gallon tank for 5 days. It seems to be established and growing as fast or faster than my 5 fancies can eat it. Only problem is I have to clear it from the intakes of my 2 biowheels sometimes, but I hope that goes away over time. Wondering if my fish are about to grow like crazy, if I should still feed them pellets, etc. etc.

The long version: Tank is going great so I gave in to temptation and added an Oranda. I was feeding my fish a lot of Hikari pellets to get the new baby Oranda used to feeding in my tank. Then my Fantail got swim bladder. The fantail is my oldest, largest, and hardiest fish so I freaked out. I steamed a bunch of peas and got ready to feed my fish peas for the next week. When I went to feed them peas the next morning, the fantail was already back to normal. I think he was just bloated from eating too many pellets. But it still made me think that I need to feed my fish more veggies, but I hate steaming veggies for them. I barely have time to cook for myself.

So I read about duckweed on the internet. General consensus is that it's a nuisance in any tank but Goldfish because it takes over. And you can't keep duckweed in a Goldfish tank because the fish will eat it before it can establish itself. Well, I bought some duckweed (lemma minor) and got it established in my tank. I watched the fish nibble on it for a couple days, then went out of town for the weekend. When I got back, the fish seemed fine. I left them a gel disc weekend feeder, which they ate. Duckweed covers the top of the tank (except for where I keep an airstone in the middle), and the fish still nibble at it. Duckweed was blocking the intake to my filters, but I cleared that pretty easily. Checked the water quality and amonia and nitrite are zero despite having lower water flow through the biowheels, and nitrates are low like normal.

I'm wondering what to do now? I'm planning to reduce pellet feeding to every other day. I'm wondering if there could be a problem with overfeeding / explosive growth due to food always being in the tank. But so far this seems like a low maintenance way to put veggies in their diet. Their buoyancy is as good as I've ever seen it. Any tips appreciated. Thanks.
 
extra surface agitation helps to control the growth rate of dw.keep feeding pellets presoaked but lessen the amount by half and see if they eat more dw.only 4-5 fancies in a 75 gallon you are fully stocked. most of the japanese breeders i have been reading about feed on bloodworms,saki hikari purple and dw.
 
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I could never keep enough duckweed in my tank for my goldfish. I would cut back on the pellets. It might increase their interest in the natural vegetation. I wish I could tell you of a way to keep duckweed from clogging the filters-- even with having goldfish which were more like aquatic lawnmowers, filter clogging can still be a problem. Scoop and throw away would be my best suggestion to keep the duckweed down. Duckweed is like Doritos-- keep crunching, it will make more. I never had a problem with swim bladder issues when I had duckweed in the tank with fancies, and I also fed them Hikari.
 
SANDYBOTTOM said:
4-5 fancies in a 75 gallon you are fully stocked.
Click to expand...

Yes I agree.

I am really loving the duckweed though. The fish are eating lots of it now, but it keeps growing. I keep one airstone in the middle of the tank, and there is a circle above it that the duckweed is slowly encroaching upon. I might add a second airstone just to leave more of the surface free from duckweed. Fish are noticeably more active. Swim bladder issues are gone. My big fantail will hover pointed straight up when he's munching on duckweed like he's showing off.

I've gone from feeding them pellets every day to every other day. I might reduce it to twice per week. I'm a little worried that the fish will grow like crazy now that they have a constant food source but only time will tell.

As for the filter, I used twine and some PVC piping to keep the area below my biowheels clear of duckweed. That has been very effective at keeping duckweed out of the intakes and out of the filters. So far I am really loving this stuff.

DUCKWEED.jpg

DUCKWEED.jpg
 
UPDATE: Goldfish eventually won the war with duckweed. They ate all of it. I was worried about duckweed taking over, so I did things to try and keep it in check like providing maximum surface agitation with airstones and not feeding them pellets.

Now I'm trying duckweed again. This time I'm reducing the airstone surface agitation, still feeding fish some pellets, and I'm going to try lots of light and Flourish Excel. Even if my fish eat all the duckweed again, I figure it can be a treat for them a few times a year. I could grow DW in my old 30 gallon tank but I'm still trying figure out what I want to do with that tank (it's empty right now). Anyway... I'm excited to see how Duckweed round 2 goes.
 
ahah I cant grow enough duckweed in my 552g pond in the summer to to supply my fancy and subukin with enough duckweed.

good luck its great stuff ^_^
 
2 orandas.1.5 yrs old. they are 5" long.i grow it out in 2 10 gallon tanks and a 4 gallon nano.i have to put new dw in daily.it is like candy to them.they munch on it all day long.bright green poop everywhere.will be adding a lionchu in the spring as soon as the breeder can ship.until then he is holding him for me.
 
hahaha I know about the bright green poop!!! My newest fish is an Oranda. He's got a while before the wen comes in but I'm excited.

This time with the DW I'm adding SeaChem Flourish Excel every 2-3 days. It's a product that really helps plants grow. I used to add it every week or so when I did water changes, but I'm hoping that if I add it every 2-3 days I can keep the DW going strong. If that doesn't work I may have to start growing DW in another tank. But I would love to be able to strike an equillibrium in my main tank where my goldies eat the DW and the DW grows fast enough to keep up with them. Also I bought a large quantity of DW off Amazon which (hopefully) will help the DW get established. If I add a little bit at a time they will gobble it all up.
 
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