A tricky one- the pale markings are complete straight lines, not broken dotted lines, but the lower flanks are spotted and show no yellow coloration. I'm wondering if this is just a particularly nicely marked Julidochromis marlieri.
It's not possible to be sure without a photo of the whole fish.
In general, a large julie with a pattern of horizontal stripes is a J. regani (J. marlieri have chequered patterns). But all the julies live in rocky areas which are separated in the lake by sandy bays and beaches, so each locality has its own distinctive colour pattern. If this fish is not cross-bred, an experienced breeder could probably tell you the exact locality it came from, because the complete pattern of spots across the lower half of the body is probably unique to regani from a particular place.
