2 dead pleco's

My 2 pleco's (approx 6+ years old each and about 6-8 inches) both just died over the weekend and will be missed.

Hoover and Eureka were THE 'explicative' at keeping my tank pristine the last half a dozen years.

The main reason posting is to get some info on why they may have died. The tank is (obviously by the ages etc) well established and in good working condition with many various other tropical community tank style fish such as some tetra, zebra, and some various different types of molly fish.

Tank size is approx 50 gal and like I said above well established and maintained.

They pleco pretty much ate whatever they wanted in the way of algae in the tank and on occaision would get a small leaf of lettuce or some other green type vegetation placed into the tank for them along with some dry sinking algae disks, this has been their diet for the last 6+ years with no problems.

Thursday last week my gf noted even though they were in the usual "hanging out" mode on the side of the tank that one of them just did not look too well and I told her they looked fine to me, plopped a couple algae disks in the tank and all was gravy. On Saturday on returning home from work I noticed that one of them was laying on the bottom of the tank not moving or breathing so I picked him out of the tank and discarded of the corpse, noting nothing unusual about the fish indicating any type of disease or illness I attributed the death to general old age, as I have no idea how long a pleco can live. Then on Sunday I notice my other one has some small whiteish patches on its nose almost looking like it had scraped away the skin and the exposed area had begun to form an ich'ish looking white area, the fish was dead within a couple hours. I did lose one of my sunset platy this weekend as well at which point I began to notice in the bottom of the tank everywhere there had been algae disks dropped in on Thursday there was this white fuzzy slimey looking masses sprouting up everywhere.

The best description I can give would almost be like a small living slimey cotton ball it looked slimey but yet had a fuzzy appearance to it. It seems to me like there was something wrong with the algae disks or they had some kind of a reation to the water for some reason. They were Hikari Tropical Algae Wafers for Pleco and Algae Eaters, the expiration date on the package (which is in some sort of Japanese or something) is listed as B.07
(some foreign text here)06.10

I have had them for about 6 months maybe as I had run out of the other kind I used to have and picked these up at my local PetSmart at the time.

They had been eating these along with the normal diet above and had no problems until I fed them on Thuraday but like I said my gf thought one of them "did not look well" but I saw nothing out of the ordinary on the first one when it passed.

Anyone had any experience similar to this or know of a possible cause?

Thanks for taking the time to read and reply, I really wanna know what happened to my pleco.......
wanted to post a pic I got of the one pleco that was left and you can notice the small whiteish spots on it's nose this was the beginning of the end.

I can but they will probably be inaccurate. I removed the dead pleco's and salvaged the neons and zebra placing them in a small desktop hex tank that I have where they have been for the past week. The 50 gal is sitting idle right now with little to no water in it waiting for me to get a day off to finish cleaning it out the rest of the way.

I just thought it very odd for them to just drop like they did when everything else lived and has been in this same state for a while with no other problems. I have had the tank and various fish for a while over the years but I guess you could say I am a newbie at heart as far as actual care of a pleco goes, I just recently found out by checking these forums that a nice piece of driftwood is also preferred for them in the tank to rasp on.

the pleco I had no idea would/could get so big, and actually started them out in a 20 gal long when I bought them 6+ years ago. The guy at PetSmart when I bought them told me they would only stay the size of the tank and 2 of them would do a good job keeping a 20 long clean. I had them live through a couple different epidemics in the tanks as I moved them from a 20 long into the current setup after my gf moved in with me (they were gtting hella big in the 20 that is another reason why I made the upgrade)

I had not added anything new to the tank, and am very sorry I cannot give a tank sample as stated above I really think it would be inaccurate as I cleaned most of the tank out and it has been sitting with just a small bit of rock, and some pretty stale water now after a week with no filtration or circulation.

I really do love the knowledge and helpfulness of this place and have been reading all the forums looking for something new to add to the tank.

nothing chnaged at all in this room/tank that I know of for quite a while. It is right behind my computer desk where it has sat for approx the last 5 years with no problems ever. Just thought it was very odd, probably some sort of a bacterial or viral as stated above. Water was probably fine as always is since the other fish seem ok since I salvaged the few neons that were left along with the zebra danio's and placed them in a small hex tank.