Plecostomus - How many pleos in one tank?

what type of pleco do you have? This is your 55g right?

 

can you upload a picture of it...different types of plecos require different care (food/driftwood/etc).

 

I can't tell by the photo what type you have (at best GUESS it's a common), so I can't give you any solid information like what temp they should be at..the ideal pH for it...whether it has special diet requirements (such as driftwood).

If I were you I'd
1) test the water to make sure it isn't a water chemistry issue using a quality LIQUID test kit. Api makes easy to use affordable ones including their popular master test kit.
Sidenote: Most local fish stores will test your water for free (ie. Petco/Petsmart)
2) make sure there's enough algae inside the tank. If not supplement it with a quality algae wafer like Hikari Brand ones. You can also feed cucumber, zucchini, and no-sodium french cut canned green beans (when I bred bristlenoses they LOVED cucumbers and the french cut canned green beans). Most plecos also eat a small amount of meat in their diet (ie. cut up shrimp, cut up earthworm).
3) Looks like you already have a piece in there, but just in case it's a fake piece I'd recommend some sort of natural driftwood in case it's a "rasping" species (Ie. Malaysian driftwood will sink immediately).
4) Provide a darkened hiding spot to help reduce stress (you can use things like a tipped over terra cotta pot, pvc tube, caves-both pet store bought and home made, etc).
5) Keep a steady water temperature (with livebearers I'd aim for 78-80F).
6) Assure good water oxygenation and movement (ie. waterfall effect of filter, powerhead to stir water, adding airstone, etc.).

 

seeing that your pleco looks to be a common pleco and will grow to 18 - 24 inches (will out grow a 55g aquarium), i wouldn't get another one. some common plecos tend to get a little lazy with algae clean up the older they get. i've got one that's about 16 inches and would rather clean up the scraps from my oscars and jack dempsey.

 

• True siamese Algae Eaters- eats green, brown, and brush
• chinese algae eater- pretty much only eats it off when young (like the common pleco)
• Bristlenose Pleco-peaceful and only gets 4"

 

how about snails ?

 

Usually they'll eat it within a day or two at the most.

 

Adding stock to take care of a maintenance issue is never advisable in my opinion, and yes algae is a maintenance issue. What type of lights are you using and what is your photoperiod? Also what type of algae are we talking about?

 

Could you post a pic, there are lots of "green" algaes spot, clado, hair just to name a few.

 

Yep