Is it easy to tell the difference between male and female Mandarinfish?
Yes. The male has an extended first dorsal ray
Can a pair of Mandarinfish be kept together?
A male and female will often get on well together in a reasonably roomy aquarium and may even mate on a regular basis. However, keeping more than one mandarin of the same sex – particularly males – in an aquarium usually results in vicious fighting  and serious injuries to both parties, and so is best avoided.

On transporting a mandarin home, the water was full of a clear, slimy substance. What is it?
When under stress, mandarins shed their mucus coating. The slime is noxious to other fish and in the wild is used as a deterrent to predators. Therefore, avoid any rough treatment and never introduce them into an aquarium where they are likely to be bullied or pursued.
Should a tank housing mandarins be covered?
Yes. When startled or in the throes of mating, mandarins can leap from the water.
Some specimens have noticeably pinched-in flanks. Is this normal?
No, this particular condition indicates that the fish has not eaten for sometime and even though it may have recently begun feeding, it will take quite a while to regain a healthy, plump appearance, given the correct food. Fish seen in this condition are best shunned as the mortality rate is high.
Will a mandarin eat nuisance flatworms?
Although there have been one or two reports if mandarins eating these flatworms, the majority will not consume them.
Given the choice between some very large and very small specimens, which would be best for an average tank?
On the whole, smaller specimens definitely do better than larger ones. Individuals of 3-4in (7.5-10cm) may be suited to a very well established invertebrate aquarium in excess of 72in (180cm), but usually they cannot locate enough food to survive for long periods.
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