For those species I'd go 8x3x3 - two extra feet of width gives a better display I feel. 6x5x3 would be great for rays, but the extra depth probably isn't necessary for regular cichlids.
For those species I'd go 8x3x3 - two extra feet of width gives a better display I feel. 6x5x3 would be great for rays, but the extra depth probably isn't necessary for regular cichlids.