I am feeding my platys ( and one pleco) Omega One freshwater flakes. Every now and again maybe a little frozen brine shrimp (they've only had this twice though). The fish sometimes have very long strands of fine poop coming out as opposed to nice chunky short ones which I think is healthier? I am wondering if their diet is OK? What do you recommend? Are they constipated? I have no live plants in the tank and so they have no greens.