Sure thing :wavehand:
Pseudanthias have a complex social structure and they are hermaphroditic. This is a one way journey from non-gender to female to male. If a dominant male perishes, the largest female of the group will often develop into a male to take his place. The quotes below discuss grouping of Pseudanthias. Some of the articles don't necessarily support what I have said persay but I think I am correct that keeping two is generally risky. The main point is that Pseudanthias establish a pecking order that can lead to severe bullying and small groups help weaker fish hide; the aggro is dispersed. I have incl. several sources to show that this thinking isn't isolated (I'm not making this stuff up!
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'If you are going to attempt to keep an anthias shoal, your chances of success will increase if the composition of the group consists principally of juvenile and female individuals. You should add only one male to the aquarium, unless the tank is large enough to accommodate more. Even then, the ratio should be highly skewed toward juveniles and/or females (a good rule of thumb would be one male to every four to six females/juveniles). Fortunately, the majority of anthias species are sexual dichromatic (that is, males and females differ in color).'
http://www.liveaquaria.com/PIC/article.cfm?aid=267
'
The Lyretail Anthias does best when kept in a group and housed in a species-specific aquarium of at least 125 gallons in size. Male Lyretail Anthias are best kept alone or with several females. Though the Lyretail Anthias generally occupy the middle of the aquarium, it appreciates the availability of several hiding places.'
http://www.liveaquaria.com/product/prod_display.cfm?c=15+20+54&pcatid=54
'One of the better and *more readily available* Anthias for the aquarium. If you want a group of Anthias, this is one of the best to go for. This species is a hardy and bold Anthias species. (Bold for an Anthias, that is.)
It is best to keep solitary individuals, or a group consisting of one male to several females, unless you have a large aquarium. Provide plenty of water movement and open swimming space. Great for reef tank.'
http://www.marinecenter.com/fish/anthias/orangelyretailanthias/
'In hobby literature, the long-touted lore of Anthias needing to be kept in groups is a bit in error. It's true that many live in very large shoals or schools in the wild, sometimes numbering in the thousands. But in specific groups and harems, there is a decided pecking order and often considerable intraspecific aggression. With their natural territories consisting of many square meters in the wild, the compression of a harem into a home aquarium results in quite an abnormal situation, regardless of the size of the display (short of public-aquarium sized displays). Weaker or more passive individuals get singled out and harassed quickly, but they cannot escape far enough away to quell the aggressor, as they can in the wild. Thus, such practical realities make us reconsider what it will take to keep (or not keep) Anthiines captively.
Give Anthias very large aquariums (at least a couple hundred gallons) to allow them a better chance of surviving a full lifespan. It is difficult to give a rule of thumb on stocking densities for the dozens of species encountered in the aquarium trade, but I'll suggest a rough guideline of one "Anthias" per 75 gallons (285 liters) of water.
I strongly encourage aquarists unable or unwilling to dedicate such space to consider keeping a single specimen of one of the hardier varieties.'
http://www.reefkeeping.com/issues/2005-04/ac/index.php
An excellent in depth article:
'Remember, with the more aggressive anthias you will consistently have the best success keeping only one specimen per tank. One of the only drawbacks in keeping some male anthias, like P. squamipinnis, in an aquarium without conspecifics is that their coloration may change and become more like that of the female. (We'll talk a little more about this later.)
The other possibility,
if you want a group of anthias, is to crowd a smaller tank (at least a 75 gallon tank) with female specimens (at least 10 individuals in the shoal). You often see this in some of the European tanks. Big beautiful tanks FULL of anthias! In this way a dominance hierarchy will be more difficult for them to maintain and rather than one or two subordinate fish being the recipients of all the abuse, aggression is spread around the captive population. Analogous I guess to what a lot of fw aquarists do with African cichlids. If you decide to try this procedure it is important to introduce all the shoal members at once. The problem with loading your tank with anthias is that you will limit the number of other fish species you can have, possibly put an excessive biological load on your filter system and increase the chances of a disease epidemic.'
http://www.reefs.org/library/talklog/s_michael_030401.html
But remember the females fight for dominence until one changes into a male. It is not unusual for anthias to die from stress in these situations.
