Expect we all have different degrees of emotional attachment to creatures living on our created reefs.
I, for one, develop a much closer relationship with each critter, the longer I have it.
There are a number of fish that have been with me since I first got into hobby.
We are extremely close.
I know their habits, they know mine.
Ever notice how they learn feeding times and go into frenzy when you approach tank during regular feeding periods and just kind of wander about and do their thing when you come close during non-feeding periods. (expect this is much more pronounced if you generally feed at same times every day.)
Also ever observe how they will come up to glass to say hello(?) whenever you or family member comes into room or come near glass...but ignore or actually go into hiding when a stranger approaches? (esp. visiting children...they know, they know...
) Even when my cats which like to perch on nearby chair and sit for hours watching and dreaming about getting in there with them, the fish used to go into hiding...but now totally ignore or put on shows for.
Losing a long held resident is a traumatic event.
Trip to LFS is best means to remedy sense of loss.
But even same kind of replacement fish is just not the same as lost one.
Its just looks different, habits are not the same and there is very little sense of attachment or emotional bonding for long period to come. Even to point of little regret if for some reason it does not make it for one reason or other, or if does not get along with other fish in tank...except of loss in $$ spent.
Usually I only give it a few days to adjust to other fish and new environment, or out it comes and goes back to LFS if does not. Existing fish have priority
Even while looking the same as lost one, other fish tank know it is a different fish and will generally harass it for a while till accepting new resident...
Enough blabbering...guess I am still in grief period over demise of my sixline.
R.I.P.
(Sixline Pics)
RE:
I Love my Sixline! 
Losing a long held fish makes me physically ill.
