visually impared mel stock?

[R.D.J. Catchpole]

Dear All,

I would be grateful if someone could help me with the following 
problem.  I need to obtain some mutant stocks of D.melanogaster 
which are visually impared for an ecological experiment.  It's very 
important that the mutation does not have any associated 
pleiotropic effects on the fitness of the stock, including their 
competitive ability.  The degree of visual acuity should be such 
that they are still able to negotiate small openings and move 
around a complex series of tubes.  This should be at a much slower 
rate in comparison to the wild type, i.e. I need to reduce the 
rate of dispersal in my system.  A white eyed mutant (w) would be 
too severe in this situation - can anyone make a few suggestions 
about likely candidates please?

Thanks in advance
Roger