(6Z,9Z,12Z,15Z,18Z,21Z)-tetracosahexaenoyl-CoA[x] + CoA[x] + FAD[x] + H2O[x] + NAD+[x] = (4Z,7Z,10Z,13Z,16Z,19Z)-docosahexaenoyl-CoA[x] + acetyl-CoA[x] + FADH2[x] + H+[x] + NADH[x] — reaction