Hi everyone..maybe someone can help or tell me what to do besides what I keep doing.
I have a 55 gallon tank, with a 60 whisper filter and the adverage temp being around 80 degrees. I have only 3 ( or 4? ) types of fish in my tank, I have a cory, a gourami and a pleco (he's 12+ inches long..) and now 29 mollies. I have bred the mollies I have now, and originally I had alot more ( you won't believe me lol) but ...now that I don't have what I thought was first overstocking..why do my mollies keep dying. I sometimes in a bad week, can loose 3 for no reason..they don't look sick, no signs of illness that i noticed and they eat.
I clean my tank weekly, with about 12-16 gallons out and the tank looks clear and clean again and in a few days..it could look cloudy again. I use to have a problem with overfeeding but i'm confused now, that can't be it..can anyone sort of help me sort this out?

The large pleco is probably part of your problem. Plecos even when they are smalled have alot of waste making the ammonia go up in your tank and will caue fish to get sick and/or die. 55gal is probably to small for your pleco now anyways :(

Try doing 50% water changes twice a week for 2-3 weeks then see where you stand on loosing them if its stopped slow down to 50% 1 time a week.

Ur bit over stocked, the pleco is too big for the tank, instead such a small water change do a 50% water change a week. If its still to foggy. Add another filter, you cannot over filter!! I have 3 filters, xp3 and to high power hang on filters and it stays clear evern with my stock. Plecos do poop a lot, so clean ur gravel or sand every time u do ur water change. Knave 30 plecos in my 100, so best keep up with the bottom cleaning.

Have you tested the basics? Ammonia, Nitrite levels? Good pet that given the stock they are your problems. Grab a some liquid test kits from the pet store (API works just fine) for $5-10 and give the water a test. If they are not 0 then you likely have the suspect in hand.

Wooow everyone ! Thanks for the advice. Well, I did actually did a tank cleaning of 24 % and it actually smelled like..a fart, oh all things. I guess possibly overfeeding happened again , .
Doing another tank cleaning 4 days it last ,cleared up the water some actually but i'm horrible at math..what exactly would 50%..of 55 gallons be?
I have some strange way of cleaning my tank that has to be old school, I use buckets or a hose but it's neither attatched to my kitchen sink ( I don't seem to have the right fitting) So cleaning isn't always easy, but I try to keep up.

I know my pleco is big..and apart of my overall problem, I'd like to give him to someone or somewhere but i'm clueless to be honest, I doubt my local Petco would accept a outside fish and in living in the desert..I dn't think anyone has a koi pond lol

I use a tote 35 gallon container. I use the gravel siphon and clean out the tank by the time I get mostly done with the gravel I would have about 20 or % of water out of the tank. Then just take the tote out side or in the tub however you get rid of it.

If you use tap water don't fill it directly into the tank. Treat the water for chlorine first. Again a tote comes in handy. You can fill up the same tote you just drained the water into again and this time add something to de-chlorinate the water. I prefer Prime but you can use what you like. If you don't add something to remove the chlorine you risk killing all the bacteria that is cleaning your water of ammonia, Nitrite, Nitrate.

As you seem to already know overfeeding can lead to problems as well. That is why I suggested getting a test kit for Ammonia, Nitrite (mainly ammonia) to see what is going on in your tank.

I once had a test kit but that was a few years ago and sadly..despite needing one, I haven't been able to afford one ( as stupid as that is given they aren't much) but yeah.. I just try to keep up with a routine of cleaning and some times I can keep on top of any spikes that I might get without knowing it.
It some times works .

No problem! Another option is if you have the time some pet stores and almost every fish store will test your water for you!

The cleaning sounds good just keep in mind to not replace all your filter media at once. When you add water (if from the city tap) just be mindful to de-chlorinate it and I think you will be ok. I don't know how it is in your area but many times you can put pets up on Craigslist to find a new home for the pleco.

Or several managable buckets (I have 4 now).

You can do daily water changes untill you get the amonia down. 25%. It takes less than 5 minutes.

Also not sure what you are doing for the filter, but you could add an another filter and or amonia removing filter media. They sell sheets of this foam that you can cut and place in your filter box. I use it- along with "over" filtration to help my goldfish tank.

I am almost sure you can re-home/donate Mollies to your lfs. Mine will take any and one offers me store credit some times. Craigslist has a pet section and you can probably get a re-homing fee out of them.

Another option would be to get a fish that feeds on baby fish. My Mollies fry never live since my bumble-bee gobys eat them all up. I assuming that is what is happening- she has been fat at least every other week since I brought her home and I have no babies and lots of plants....

Good luck-

Julie

Haha, well I have 4 ,four gallon buckets that I sometimes use and a long hole that I connect to my gravel syphoner and put it out my front door.I always use a dechorinator or leave the water in my water jugs for a day or two. I actually like my mollies, and bred them two years ago to have the mollies I have now, and if anything i'd like to rehome my pleco but in my craigslist I don't know if anyone would want one. I see fish listed and I want to get it for a bigger tank, not really to adopt a fish, lol , so i'm hesistant to even try to put my pleco up since I would like him ( i think it's a male) in another place. my brother got me him without knowing it would get big and bigger and didn't listen really when I said I didn't want another pleco when our last one died , he was big to. But he starved sadly because I had alot of bottom feeders and scavenger fish before the mollies.
I culled out my males a year ago so i wouldn't have any more breeding unmanaged because I was having a hard enough time and my only gourami actually wouldn't eat any of the mollie fry when they were little, I think he was overwhelmed by the numbers or thought he was one

Well it sounds like you are doing a really good job then! Given what we know about your stocking I would lean in that direction as a reason for fish loss. No way to know for sure without getting the water tested but it is a good bet.

Maybe an additional filter would do it then?

People who have large tanks love the large pleco's. There are many varieties that don't get as large as the one you have- so you might check it out. I am waiting on some albino bushy noses from another local fish person I met on here. He said they stay under 4". I was looking at clown pleco's yesterday (another under 4" variety).

Good luck to you- Julie