The plecos are really fat they get veggies and wafers and a varied diet. But i think i found out whats going on. Today the ligh strip stopped working, this light strip was given to my husband a while ago and he ws told that it was "great" for plants. (he doesnt know about plants, he just tried it for like a week) so i believed him that it was a great light strip. Today since the light went out i look to see what bulb it has to replace it...it has a 6,500l 45watt coralife bulb. I dont think thats enough light for a 29g considering that my 10g planted alone has 10,000k 50watts. Could it be the plants are dying and the fish are eating the rotted plant matter not the plant itslef? and thats why i see it slowly disapearing from the bottom up?