Thanks guys. Wanted to make sure everything was going smoothly again before posting back on here.
Found a vet who finally knew what they were talking about (small exotic pet specialist) and he diagnosed dropsy. Every other vet i called didnt seem to give a toss about fish at all. he gave me an antibiotic (Tribrissen) to use but said that once they puff up they are almost destined to die. Now i had already lost one 9cm+ Linangu and another of the same size had gotten very puffy. I wasnt about to give up on it since i have had soo much trouble finding any others I have been treating the whole tank as recomended and treating the sick fish in a 2lt bath for 12 hours per day as prescribed. All the other fish in the colony are fine and are back into breeding mode and the best thing is that the sick Linangu is all better also. I have another 2 days to go treating the whole tank but so far (fingers crossed) all looks good.
As for feeding and water quallity, i feed small amounts three times a day and culture algae in a spare tank on rocks/logs to feed once a week. The algae is what the vet suggested to be the likely cause as i have a very very strict maintenance routine on my 12 tanks (only keep tropheus) and the fact that i have more than sufficiant filtration on all tanks. So for now i will halt the algae feeding even though it seemed to being on big bursts of breeding activity.