Advice? Should I add a fuge?

It's always good to add water volume to your system. I like refugium for a good place for pods and many other things to grow. It's pretty much a must if you want to keep a mandarin Ling term.

 

Mandarins will also eat live foods. Black worms for one, or brine shrimp.

Black worms die shortly after hitting SW, but fish go nuts for them.

White worms are another option, stay alive a lot longer, but are generally harder to find.

 

personally you won't have a system big enough or aged enough to have a normal mandarin you buy at a store ....... But if you can fine one that eats brine then there is another story, in a 55 what fish do you have or plan, I suggest slow eaters for one. When you go into stores ask them to feed it and visually watch it eat. If you don't see it eat for any reason it won't survive....... The green target mandarins are a little smaller than a blue but there both the same when it comes to size of the tank..... Good luck mate

 

@aussie ill have to disagree with you about the system not being big enough. I have a 40 breeder with a 20 long sump thats been through hell and back and i successfully have kept a 2 manderans <not at the same time> and he is pretty fat. The first one I kept for at least 6 months before my skimmer pumped all my water on the floor and crashed my system. So i gave that manderan away to bwg777. I just got this guy 2 months ago and even moved the tank to a new apartment a month after I got him. But he's still kicking.

 

Does it eat brine ?

 

I have never heard of a bad reason to add a fuge

 

@aussie not that i know of.

 

I think fuges on smaller tanks are mainly to assist with some algae control. Depending on the size you make it may not make a huge difference with the amount of pods you'll have but you should always have pods if you have fuge. Hope that makes sense.

As to the mandarin, I have a 20g with no sump, no skimmer, that has a red mandarin and a six line and they've been together about 4 or 5 months now with no issues. Honestly I'm not sure what the mandarin is eating but he's not super skinny so I'm not worrying.

 

I agree, I'm not really sure of any real big reason a fug is a bad thing.