# Black and gold mollies eating algae



## Alicia (Nov 8, 2011)

I was in my local fish store looking for something to help with my blue/green algae when the assistant told me just to get some mollies. He took one of the plants from the plant tank which was covered in black algae and put it in with the mollies. Those fish descended on that plant and while I was watching they were cleaning the algae off the plant. He assured me that they would eat any algae but I wanted to get some opinions here on the subject before I rush out and buy more fish.


Has anyone had experience with these fish eating algae?


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## Drewet88 (Dec 21, 2015)

I used to keep mollies before I switched to guppies (tried keeping them together but the mollies would stress out every time). I never had an algae outbreak big enough to know for sure, but I do believe I seen my mollies nibbling at plastic plants and other decorations so maybe they were trying to eat algae. 

What other fishes will be kept with the mollies?
IME they stress out in community tanks but it could've been my setup. (My platys stressed as well when added to my guppy tank so maybe its just natures way of telling me guppies only). Your results may vary.


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## Alicia (Nov 8, 2011)

Drewet88 said:


> I used to keep mollies before I switched to guppies (tried keeping them together but the mollies would stress out every time). I never had an algae outbreak big enough to know for sure, but I do believe I seen my mollies nibbling at plastic plants and other decorations so maybe they were trying to eat algae.
> 
> What other fishes will be kept with the mollies?
> IME they stress out in community tanks but it could've been my setup. (My platys stressed as well when added to my guppy tank so maybe its just natures way of telling me guppies only). Your results may vary.



I have tetras and dwarf gorami with one bristlenose algae eater who is obviously not doing his job, the tank is heavily planted I've had it for several years and this is the first time I've had a problem with algae like this. This stuff is growing overnight after I remove it as much as I can.


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## Drewet88 (Dec 21, 2015)

I found this link that might help you.http://www.plantedtank.net/forums/2...first-hand-account.html?nocache=1451383273226

It says black mollies only eat algae when underfed so I don't know if it's the best option but try the American Flag Fish if you can keep it/find it.


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## Nordic (Nov 11, 2003)

When they are "eating" algae, they are mostly after microorganisms living on it.


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## Alicia (Nov 8, 2011)

Drewet88 said:


> I found this link that might help you.http://www.plantedtank.net/forums/2...first-hand-account.html?nocache=1451383273226
> 
> It says black mollies only eat algae when underfed so I don't know if it's the best option but try the American Flag Fish if you can keep it/find it.



Thanks for the link. I don't think I'll be getting the mollies I don't like the idea of underfeeding. I'll look for the American Flag Fish but I have to admit I've never heard of it. 


I did get a Finnex Planted + light fixture some time ago and I'm thinking the lighting may be too much.
Thanks again for your help.


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## Axelrodi202 (Jul 29, 2008)

If you're dealing with cyanobacteria (blue green algae), then nothing will eat that. Try increasing nitrates and water flow; if your infestation is far-blown than antibiotics (erythromycin) may be needed).


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## Alicia (Nov 8, 2011)

Axelrodi202 said:


> If you're dealing with cyanobacteria (blue green algae), then nothing will eat that. Try increasing nitrates and water flow; if your infestation is far-blown than antibiotics (erythromycin) may be needed).




It is all over the tank but I hesitate to use antibiotics since I wiped out my whole tank of fish trying to treat Ick. I'm getting desperate though since I've removed everything including digging up some of the plants and hand removing this stuff but the next day it's back again. I have some Paraguard do you think that would help?


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## Drewet88 (Dec 21, 2015)

Alicia said:


> > Thanks for the link. I don't think I'll be getting the mollies I don't like the idea of underfeeding. I'll look for the American Flag Fish but I have to admit I've never heard of it.
> 
> 
> I also never heard of the American Flag Fish but from what I read they are easy to care for but can be semi-aggressive (it is a killifish). Its something to look into if your tank will be okay with it.
> ...


Yeah it could be the extra light, that is something else I read online to try and combat it. It said Starve the Little Buggers:
The second method, while more work and time intensive, has no real negative effects on the tank itself. In fact, it is, in general, good for the fish. The first thing to do is to thoroughly clean every surface of the tank. Second, step up water changes to lower the phosphorous levels in the tank. If your water supply normally contains phosphates, you may want to invest in some phosphorous-removing filter media. Third, kill the lights for several weeks. Fourth, feed your fish less. Most fish food contains phosphorous, which ends up in the water, feeding the cyanobacteria. Combined, these actions should starve the cyanobacteria out of the tank. This procedure takes time, of course, which is its greatest downside.
During either procedure, it is a good idea to remove the bacteria as it appears. You can often get it with the vacuum if you lightly scrape at the sheets with the edge of the vacuum attachment.

Above is a quote, not my writing but if you don't want to try antibiotics that may be your only way. If that fails then you might have to listen to @Axelrodi202 and get some erythromycin.


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## Axelrodi202 (Jul 29, 2008)

Alicia said:


> It is all over the tank but I hesitate to use antibiotics since I wiped out my whole tank of fish trying to treat Ick. I'm getting desperate though since I've removed everything including digging up some of the plants and hand removing this stuff but the next day it's back again. I have some Paraguard do you think that would help?


If it's all over the tank then it's probably very established. In such a case the standard treatments of improving nutrient/water flow conditions, manual removal, or multi-day blackouts will not work - it will come back with a vengeance mere days later. I have used erythromycin in the past and my plants and fish were absolutely fine (granted the tank had an extremely light fish load). I dose largely based on the instructions on the package, but with a few less water changes (my tank is very large). After the treatment is done make sure to suck out all the dead algae to prevent ammonia spikes, lest you find yourself dealing with other types of algae blooms.

There are many threads here and other pages on the internet detailing the use of erythromycin for cyanobacteria treatment. Like you I was originally hesitant to use antibiotics, but after my own experiences and seeing many others', I firmly believe that short of a complete tank tear-down erythromycin treatment is the only way to truly conquer a severe BGA infestation. I only wish I had started it earlier instead of undergoing a months-long drawn-out cycle of manual removal and black-outs to no avail.

Here's a nice page that talks about the science of BGA and different treatments.


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## Alicia (Nov 8, 2011)

Axelrodi202 said:


> If it's all over the tank then it's probably very established. In such a case the standard treatments of improving nutrient/water flow conditions, manual removal, or multi-day blackouts will not work - it will come back with a vengeance mere days later. I have used erythromycin in the past and my plants and fish were absolutely fine (granted the tank had an extremely light fish load). I dose largely based on the instructions on the package, but with a few less water changes (my tank is very large). After the treatment is done make sure to suck out all the dead algae to prevent ammonia spikes, lest you find yourself dealing with other types of algae blooms.
> 
> There are many threads here and other pages on the internet detailing the use of erythromycin for cyanobacteria treatment. Like you I was originally hesitant to use antibiotics, but after my own experiences and seeing many others', I firmly believe that short of a complete tank tear-down erythromycin treatment is the only way to truly conquer a severe BGA infestation. I only wish I had started it earlier instead of undergoing a months-long drawn-out cycle of manual removal and black-outs to no avail.
> 
> Here's a nice page that talks about the science of BGA and different treatments.




Thank you so much for your help and the link. I did go to the pet store today and they didn't have erythromycin so I've ordered some. I've tried frequent water changes, I've pulled the pants up and removed the stuff by hand and boiled the rocks so I think I have to give the antibiotics a chance.
I reallyappreciate your input.

Bump: Thanks everyone for your help in trying to get rid of this pesky stuff. I've learned a lot about this which I now realize I'm not going to get rid of just by changing the water and removing by hand.

Happy New Year to everyone!


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## PlantedRich (Jul 21, 2010)

Do be aware of what happens when you do kill algae. I let it sneak up on me recently even though I knew. Dead algae is there and it does decay. I removed all fish and plants, turned out the lights and left it set for four days and then found a smelly ugly sewer! Had there been any fish in the tank the ammonia would have killed them for sure. 
Dead organics will shoot the roof on ammonia so be ready to deal with that when you have to do any major treatment. check carefully before using any meds so that you are prepared for any nasty effects it may have. 
My doctor keeps reminding me that we are still "practicing medicine". That goes double for the fish hobby.


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## prototyp3 (Dec 5, 2007)

I can say that the black mollies are pretty amazing algae cleaners. I put two males in a 75g that was battling hair algae, and they immediately tore into it. They rasp at the leaves, rocks, and even gravel. What they don't actually eat just gets pulled to the filter intake, so you can mechanically remove the remnants. Waaaaay better than Amanos, and cheaper. 

A nice bonus is they pull double duty, and perform as surface skimmers!


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## Diana (Jan 14, 2010)

Mollies will not eat Cyanobacteria. 

Mollies are hard water fish, and can live in salt water (brackish to full marine conditions). They do not do well in soft water. 

Mollies can be aggressive toward each other. I had a female claim all of a 4' long tank. Would not allow any other Mollies in there. On the other hand I have had a dozen in a smaller tank, and they got along fine. All too well, actually- I ended up with several dozen. 

Mollies will eat diatoms (brown algae). 

To clean up Cyanobacteria I would clean the tank well one last time, including the filter. Then follow the full course of treatment with Erythromycin. I believe it is a 5 day treatment. Monitor the water conditions. If you need to do a water change, re-dose the Erythromycin. 

Also, try to figure out why it is growing. I usually see it in the slowest moving water areas of the tank.


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## Hooked on fish (Dec 15, 2015)

Mollies do eat algae and some plants... Mine use to eat java and Christmas moss.

Mollies are great but personally I like guppies.

My "farm" tanks are also my grow out tanks for guppies.
If I have plants with extra algae on it, I put them in there and the guppies will keep it in check.

The young ones better than the older ones.


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## discuspaul (Jul 27, 2010)

You said your BGA was 'all over the tank'. If you mean that the cyano pretty much covers the bottom areas of the tank, mainly the substrate, here's an effective way of dealing with it fairly safely, and without using antibiotics:

Turn off your filter(s) - lower the tank water level to the point where you can easily reach the bottom areas heavily laden with the BGA.
Spot dose every area of the cyano - at close range - using a plastic syringe, or test kit pipette, with plain household H202 - hydrogen peroxide. Shouldn't harm the fish whatsoever if you take normal precautions to keep them from getting a snoutful while you're dosing, and you don't use excessive amounts in a single dosing period - space it out doing parts of the tank on successive days if need be.
You'll see air bubbles accumulating on the cyano, which will soon begin moving off & rising to the water surface - a sure sign it's working ok. When you've done all you feel comfortable with doing, leave the filters off for at least another half hour or more to allow the peroxide to remain in place & do it's job.

Refill your tank & re-start the filters.

The following day, the BGA where you've dosed the H202 should have disappeared. Repeat the procedure over the next day or two till you get all of it (assuming you had a lot.)

Then you need to fix the main underlying cause of the BGA developing in the first place, a lack of proper circulation within the tank generally and in the bottom substrate area in particular. 
While adding a power bar, or a an active airstone may help, the most effective remedy is to add a circulation pump , properly positioned, to keep a reasonable good water current flowing over the areas where the BGA developed in the first place. It will also help to improve on your tank cleansing/substrate vacuuming routine as well.
A Hydor Koralia pump does a great job improving or providing water circulation.


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## jehanzebanwer (Jul 27, 2021)

I read on this post that almost all mollies eat algae but they shouldnt really be considered as algae eating machines whom you can rely on 100% to clean the algae from your tank.


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## Kubla (Jan 5, 2014)

Everybody keeps talking about algae but the thread is about Cyano*BACTERIA. *A lot of regular algae treatments don't work. Discuspaul has shared instructions for dealing with it with hydrogen peroxide. I had a horribly infected tank that I successfully cleared this way with no harm to any critters. Erythromycin works but you're dealing with the issues of antibiotics and it's many times more expensive and harder to source than H2O2.


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