sorry for ignoring this thread i passed it up a couple of times and decided to leave it be.. because someone else beside me would drop a DIME on this thread... but... here is my 2pennys... well hrough my expierience i noticed the same thing in my tank... a lil white stringy worm just dangling/free swimming in my water/tank but never anchored on to any of my cichla... the worm is definitly a parasite but harmless to your fish!!! i know it sounds odd but its the truth if we are on the same page and i do believe we are... well the worm/worms develop in your tank due to overfeeding and not thouroughly cleaning your gravel/substrate... so its feeding on your leftover food thats in your gravel/substrate... IMO im a person that if i see something wrong i will get it fixed and in your case even if the worms are harmless, i would fixed it to protect my fishes health... so,, proper procedures that i went through to clear them out is 45% w/c... 20%w/c the next day... 10%w/c the following day... and finalizing it with a 5%w/c the day after... and then adding coppersafe 35% of gallons of water, depending on tanks SIZE.. i strongly hate medication.. and coppersafe is very strong so pls UNDERDOSE.. to prevent any deaths.... (coppersafe, kills everything in your tank, as far as parasites) and its in your water system for 30 days..
but like i said its due to OVERFEEDING, and NOT a THOROUGH gravel/substrate cleanse...and FYI no need to OVERFEED.. because in my tanks.. if some of my CiChLA dont eat TUFF LUCK BETTER LUCK NEXT TIME... and they do.. they are getting theyre share... BELIEVE ME.. its like they take TURNS... HAHAHAHAHA..... I HOPE I HELPED ANSWERING YOUR QUESTIONS... so make sure you get that syphon out and clean that substrate cuz thats where all parasites live!!!