blue spotted Sea Slug???

[nugg91]

I have a hair algae problem and I have heard that these are really good at ridding a tank of this....but first a few questions:

is this true?
will the slug die after my hair algae is gone or will it move to other forms of food?
are they reef safe?
will a 20 gallon tank be enough volume to even keep it?

 

[greenbean36191]

Do you have a picture or scientific name for this slug? The only blue spotted slugs I can think of that would eat algae are a few of the sea hares. Some of them probably wouldn't touch hair algae, and the one that might wouldn't be a good candidate for a 20g.