Are "Tally-ho" and "no joy" acceptable ATC terms for civil operations?
As a private pilot, I have heard "Tally-ho" and other pseudo (British?) military phrases used when talking to ATC.  I understand "Tally-ho" to be equivalent to "target(s) in sight" or "inbound" or even in some cases "affirmative", and that's the problem.  It is important to be clear and precise when communicating on the radio, however, the folks working at ATC seem to understand these phrases.

FAA:

I've read the AIM - Aeronautical Information Manual and Pilot's handbook of aeronautical knowlage (Both available for free download from the FAA's website) and I don't remember seeing these phrases anywhere.

Other texts caution against using these colorful phrases instead of standard phraseology because problems stemming from varied interpretations.  It is important to be clear and precise when communicating on the radio. 

I think the correct terminology is: "Traffic In Sight" and "Negative contact"