(Please check out the entries under that topic in the Guppylog Quicklinks - to be found in the upper right hand box on the home page.) Also, what temperature is the aquarium kept at?

However, I have a bad feeling about your algae cleaner. It is not fair to expect new aquarists to know all about the fish. Sometimes the folks working in the shops don't know much more. Other shop owners know, but don't warn customers about the behavior, diet or ultimate size of their purchases. (Then when fish die, the customer returns for more.)

It is not always easy to do, but take a 3x5 note card, your personal planner or whatever you jot notes on (where's that old envelop?) before you purchase a new fish or fishes. Jot their names down. Either stop by the library for a good fish book, go on-line (Google is your friend, we can help here too) or buy a good aquarium reference book.

For a recent article on books on GL, please check out:
http://www.guppylog.com/story/2004/12/28/182048/67

That book for newbies can be borrowed through an inter-library loan. It may also make a nice present to your girlfriend. ;)

Now, I have a real question as to what that algae eater is. I also have a question as to why you felt (or your fish dealer felt) that you had to have one just now. I'm surprised that they would suggest adding more fish when your tank's nitrogen cycle is still developing during that crucial first month.

Was there any algae to eat in the tank? Even a "plecostomus" (probably a Hypostomus species) needs a lot of veggie bulk. If it is not there, they need a bunch of flake food on the bottom of the tank. Since most of them in the shops are really starved, it is even remotely possible they would bother your guppies if there was no other food source.

It is more likely that the algae eater you purchased was a so-called Chinese algae eater (Gyrinocheilus aymonieri). They are common in the trade, but shouldn't be so.

Your Chinese algae eater will be true to it's name for a while. Then as it grows (towards 1 foot) it will become a bully, chasing and sucking body slime off of other fish. :(

If it has nothing to eat, it very possibly will go after your guppies now. All creatures have an imperative to try and survive, unless they are really, really sick.

Watch to see if that creature is attacking your guppies. If it is and you still have a plastic bag from the shop, catch that fish, put it in the bag with a couple of inches of water (leave it open) and float it in the tank. Call your shop and ask the proprietor or manager if they will take the "Thai slime sucker" back.

If they will not, put the fish outside (if it is as cold as our 10 degrees F at the moment) and the fish will perish pretty quickly. Then make a quick  set of calls to your local Chamber of Commerce and
Better Business Bureau and note that said retailer seems inclined to sell unsuspecting customers, fatally incompatible fish.

There are a lot of tricks which can limit algae in a tank without having to buy a "working fish". One is having plants which will absorb the nutrients the algae would use. Secondly, be as faithful as possible in changing 30-40% of your tank's water with "seasoned" water every week.

A third suggestion is that if any algae grows on the tank sides and you don't like it, cut down the hours your tank light is on. If a lot of light is coming in from a window (perhaps while you are at work - check on the weekend), then a tank background or even white paper can be taped to the side/back of the tank where the sunlight is entering.

Don't use black paper facing the sun because it could absorb a lot of heat. White on the sides, like light gravel, can cause your fishes' colors to fade. I'm planning on using white posterboards on the back of a large living room tank. I will figure out how to either tape a dark blue paper or standard tank background inside of that posterboard, facing the tank. Oh yes, don't use construction paper, because that stuff bleeds color all over the place!

If a little algae forms on the front of your tank, it can be easily removed with a soap-less plastic pot scrubber inexpensively picked up at your grocery store. Rinse it thoroughly before first using it. Dedicate it's use just to your tank. :)

You guppies will actually eat some of the scraps. The rest can be removed with a gravel vac.

Green algae is actually a sign that your tank is reasonably healthy. It is one of nature's ways of cleaning up an excess of fish waste material. If you were to find that green-blue slime, a cyanobacteria, then your tank has a serious pollution problem. Even that can be effectively dealt with though (through physical removal and militant gravel vacuuming). I have been amazed to see fish reproducing around that stuff. I guess sometimes the fish don't read the books.

Good luck! Please let us know what that "algae eater probably is.