Goldfish and algae-eater compatibility

Question
QUESTION: Hi i have had a black moor named Harvey for about a year now
and i decided to get another fish too. i went to pets mart
and bought an algae eating fish,small, and put him in the
same tank. I really care about my fish and I'm scared I
should not put them in the same tank and if I should I don't
know what the environment should be like, the sales lady
told me it would be ok but i just want to be sure?!?!? Can
you help me?

ANSWER: Hi Sarah,
If the algae eating fish is small such as Otocinclus Catfish.  There is a chance he will be eaten by the goldfish if it is small enough to fit in his mouth.  Goldfish have a voracious appetite and will eat anything.  As long as the pleco is does not fit in his mouth it will be ok.  
-Matt-

---------- FOLLOW-UP ----------

QUESTION: the problem is i am not sure if he can. my goldfishes mouth is
about the size of a rasin and my other fish is about that
round but a little larger and is about 2 inchess long.....

ANSWER: Could you raise him in another tank until he is big enough or buy the same species but a size a bit larger?  If you are unsure, I wouldnt take that risk.  You will end up having an expensive meal for that goldfish :)
-Matt-

---------- FOLLOW-UP ----------

QUESTION: Thank you soo much Mr.Dao!!! you have been such a big help!!
Im going to put him in a glass coffee pot with do decor in
it for a night or two until my friend can loan me her old
fish tank!!! he has food and all the stuff he will need but
i do have on last question: sometimes he will swim and then
freeze and just float and i get nervous every time and i
just want to know is it normal?

Answer
Does he float up on his own?  Like he cant control his buoyancy?  If this is the case there is something wrong with his swim bladder.  It is commonly due to constipation.  To treat it, you can feed cooked mushed peas.  Fish should be fed peas once every week anyway because peas have been researched on fish to relieve this symptom.  It is still unclear how it can do this other than providing fiber but whatever works works right?  

But this is only if he is losing control of his swim bladder.  Monitor him more closely and feed him peas anyway as a precaution.  

-Matt-