Your lighting is minimal for the size tank you have. You are getting about 1 watt per gallon. Kenya's are fairly easy and forgiving. It is commen for the kenya to shrivel and then spring back again. Mine will do that every now and again, and they strivel when the lights go out too! There is nothing you can do unless you upgrade your lighting. Sounds like the kenya is sustaining, it simply is not thriving. It may just live as is in your system and not grow very much.