What does it mean when people say Pleco's will "foul" small tanks?

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cherryshrimp

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I rescued a BN pleco and its been in a 20 gallon for some time now. Nitrates are always under 25-30, and I never detect any ammonia or nitrite. The fish in the tank aren't super healthy. Could it be that the pleco is "fouling" the water? Is there more to fouling the water than what I can detect with my test kit? Bacterial build up in the water?? Thanks for any and all advice!!
 
If the tank looks fine and the numbers are coming out ok. A Nitrate of 30 is probably where your seeing the extra poop from the Pleco's. Does the tank smell really bad like poop? I find my biggest poopers to be my biggest fish - the Dojo - Loach - so much for actual size being 5", I have some (at least) 8 inch ones. They don't necessarily poop more but they are adept at rearranging your tank for you, loving bubblers and eating you out of house and home. (my favorite fish) If you turned a walrus into a snake, you would have a dojo. They likely poop a lot. I don't even notice my 5 plecos poop (I have 5 in two tanks)

How often do you do a water change and how much? I do weekly water changes of about 75% and sometimes have to put back 3 or 4 buckets just to have time to really clean the foul substrate (black clay). My 50 gallon is sparkling clean - a sight to behold. While I constantly have problems with foul water in my 2 29 gallon tanks. So I'll be moving up to a larger filer or putting a canister filter as soon as I can get over the prices and cough up the money or I could go with the hang on back filters of a larger size.
 
Plecos 'fouling' the water doesn't mean they do anything special that makes water bad or that's undetectable, just that they're a fish with a relatively high bioload (eat a lot and so produce a fair amount of waste) which can be overwhelming and need a lot more maintenance in a smaller tank. They also tend to shift things around like the substrate, plants and decor, which can stir up mulm if the tank isn't well maintained.

So nope, if you're not picking up ammonia or nitrites, and nitrates are staying below 30, your pleco isn't causing a problem, and 20 gallons is probably about the minimum size tank that can handle a pleco. You wouldn't want to put a pleco in a ten gallon, since it would be too small for the fish, and the relatively high bioload could be a problem in a tank half the size of yours.

What problems are you seeing in the other fish? What are they, how many, and can you share photos of them and the tank please? Someone may be able to let you know what's going on with them.
 
Plecos 'fouling' the water doesn't mean they do anything special that makes water bad or that's undetectable, just that they're a fish with a relatively high bioload (eat a lot and so produce a fair amount of waste) which can be overwhelming and need a lot more maintenance in a smaller tank. They also tend to shift things around like the substrate, plants and decor, which can stir up mulm if the tank isn't well maintained.

So nope, if you're not picking up ammonia or nitrites, and nitrates are staying below 30, your pleco isn't causing a problem, and 20 gallons is probably about the minimum size tank that can handle a pleco. You wouldn't want to put a pleco in a ten gallon, since it would be too small for the fish, and the relatively high bioload could be a problem in a tank half the size of yours.

What problems are you seeing in the other fish? What are they, how many, and can you share photos of them and the tank please? Someone may be able to let you know what's going on with them.

Colin has helped me extensively actually. The tank has tapeworms or threadworms, which is the main problem. I am currently following his recommendation of Prazipro and Levamisole. I have been fighting this for 6 months, I hope and pray this solves the issue.

I ask this question because the guppies have some fin rot, which just never heals. They nip each other endlessly, its exhausting. I'll chalk this up the stress they are under from the tapeworms though. Hard to beat the fin rot with a worm infestation...
 
If the tank looks fine and the numbers are coming out ok. A Nitrate of 30 is probably where your seeing the extra poop from the Pleco's. Does the tank smell really bad like poop? I find my biggest poopers to be my biggest fish - the Dojo - Loach - so much for actual size being 5", I have some (at least) 8 inch ones. They don't necessarily poop more but they are adept at rearranging your tank for you, loving bubblers and eating you out of house and home. (my favorite fish) If you turned a walrus into a snake, you would have a dojo. They likely poop a lot. I don't even notice my 5 plecos poop (I have 5 in two tanks)

How often do you do a water change and how much? I do weekly water changes of about 75% and sometimes have to put back 3 or 4 buckets just to have time to really clean the foul substrate (black clay). My 50 gallon is sparkling clean - a sight to behold. While I constantly have problems with foul water in my 2 29 gallon tanks. So I'll be moving up to a larger filer or putting a canister filter as soon as I can get over the prices and cough up the money or I could go with the hang on back filters of a larger size.

No smell from the tank. I do about 50% weekly changes. My tap ph is 8.5-9 and the tanks run at 7.5 so anything larger than a 50% water changes causes a large ph swing in the tank. Its unfortunate, but 50% seems to work well for keeping nitrates down.
 
Colin has helped me extensively actually. The tank has tapeworms or threadworms, which is the main problem. I am currently following his recommendation of Prazipro and Levamisole. I have been fighting this for 6 months, I hope and pray this solves the issue.

I ask this question because the guppies have some fin rot, which just never heals. They nip each other endlessly, its exhausting. I'll chalk this up the stress they are under from the tapeworms though. Hard to beat the fin rot with a worm infestation...
Fin rot can be persistent, I'm sorry to hear of your struggles! Livebearers are so often carrying worms without showing signs for months, then they can't handle it anymore and start to go downhill. Had to treat all of my tanks thanks to guppies bringing in worms, you're using the right meds to sort it, so that's good.

How long have you been using prazi and levamisole now? How often are you changing the water?
Also how dense is the planting in the tank? Are all of the guppies male? If you watch them, do you have one or two that are the biggest bullies?
 
Fin rot can be persistent, I'm sorry to hear of your struggles! Livebearers are so often carrying worms without showing signs for months, then they can't handle it anymore and start to go downhill. Had to treat all of my tanks thanks to guppies bringing in worms, you're using the right meds to sort it, so that's good.

How long have you been using prazi and levamisole now? How often are you changing the water?
Also how dense is the planting in the tank? Are all of the guppies male? If you watch them, do you have one or two that are the biggest bullies?

Yes they've had these worms since I got them 6 months ago. Just wish I could have diagnosed it earlier. The fin rot showed up much before signs of internal worms, so I kept attacking the rot and nothing worked. Once the pleco started producing endless poop with little tapeworm eggs in it, thats when things started clicking into place. Colin helped me diagnose, advising I run treatments of Prazipro and levamisole for 3-4 weeks.

I've done one treatment of Levamisole, and just now finishing the first treatment of Prazi pro. I will do water changes, run carbon and start with Levamisole again early next week. I'll probably do each 4 times just to be safe. Colin has been right again in telling me to treat all the tanks in the house. I just noticed loss of coloration and stringy poop in the rainbow tank a few days ago so I will treat all 3 tanks with 4 doses of prazipro and Levamisole. Hopefully that will put this all in the rear view.

The gh is 8-9. I use seachem equlibrium to maintain a steady gh. Unfortunately my tap comes out 9ph, 0gh, 0kh. I kept the guppies in soft water when I first got them, as I was a very novice fishkeeper. I'm sure those 1-2 months in 0gh water didn't help much with these worms... sigh...
 
Unfortunately my tap comes out 9ph, 0gh, 0kh. I kept the guppies in soft water when I first got them, as I was a very novice fishkeeper. I'm sure those 1-2 months in 0gh water didn't help much with these worms... sigh...

Eh, the water hardness probably wasn't anything to do with the fin problem, hardwater fish kept in soft water suffer problems from the lack of minerals, it's more a long term problem that affects them internally, and shortens their lifespan. You wouldn't see visual evidence after just a few weeks in soft water. You're far from the only person who hasn't known about the importance of GH either, I kept otos (soft water fish) in my hard water for nine months, oblivious, since they seemed to be thriving, until I came here and learned about water hardness and the effects in has. I now have them in softer water, but I did lose three with no other obvious cause over the next few months. For soft water fish, the excess minerals in hard water build up internally, eventually causing internal damage like blocking their kidneys. There isn't anything you can see externally, they just pass away much sooner than they should.

For worms, you need the right meds, nothing else will get rid of them. But you have the right meds now :)
I have to add a note of positivity, I saw the zebra danios breeding for the first time in months, pretty much since I added the guppies. This gives me hope the Prazi and Levamisole are working. Now just to beat the fin rot...
Hmm, I'm suspecting that this isn't 'fin rot'. I reckon the danios are shredding the guppies fins. I tried some guppies in a tank with some schools of tetra and zebra danios for a short while, and the guppies tails were shredded, just like the ones in your last posts. I don't know for sure whether it was the neons or danios, but I once I moved the guppies into a different tank, no danios or tetra, their tails healed up just fine. Had no issues with guppies in any of my other tanks, only in that one. It was other fish shredding them, not the water.

Sorry, it's hard to keep track since you have a bunch of different threads, but what's your complete stocking? What size tanks, with how many of what fish? Want to try to help you fix this, and it's better to rule out the simple things before throwing different meds at them for fin rot after treating the worms, only to discover later that it's not bacterial or water quality, but danios tearing their fins, or the male guppies ripping each others tails. Especially since you've been trying to battle this for six months and nothing has worked before... makes it even more likely that it's the danios or something else in the tank with them. Worms don't cause fin rot or torn shredded fins.
 
Eh, the water hardness probably wasn't anything to do with the fin problem, hardwater fish kept in soft water suffer problems from the lack of minerals, it's more a long term problem that affects them internally, and shortens their lifespan. You wouldn't see visual evidence after just a few weeks in soft water. You're far from the only person who hasn't known about the importance of GH either, I kept otos (soft water fish) in my hard water for nine months, oblivious, since they seemed to be thriving, until I came here and learned about water hardness and the effects in has. I now have them in softer water, but I did lose three with no other obvious cause over the next few months. For soft water fish, the excess minerals in hard water build up internally, eventually causing internal damage like blocking their kidneys. There isn't anything you can see externally, they just pass away much sooner than they should.

For worms, you need the right meds, nothing else will get rid of them. But you have the right meds now :)

Hmm, I'm suspecting that this isn't 'fin rot'. I reckon the danios are shredding the guppies fins. I tried some guppies in a tank with some schools of tetra and zebra danios for a short while, and the guppies tails were shredded, just like the ones in your last posts. I don't know for sure whether it was the neons or danios, but I once I moved the guppies into a different tank, no danios or tetra, their tails healed up just fine. Had no issues with guppies in any of my other tanks, only in that one. It was other fish shredding them, not the water.

Sorry, it's hard to keep track since you have a bunch of different threads, but what's your complete stocking? What size tanks, with how many of what fish? Want to try to help you fix this, and it's better to rule out the simple things before throwing different meds at them for fin rot after treating the worms, only to discover later that it's not bacterial or water quality, but danios tearing their fins, or the male guppies ripping each others tails. Especially since you've been trying to battle this for six months and nothing has worked before... makes it even more likely that it's the danios or something else in the tank with them. Worms don't cause fin rot or torn shredded fins.

I appreciate your responses. Most of the time posting on these forums I get very little help.

The danios are much too busy chasing each other than the guppies. Since I've lost guppies over the months, I am down to just 4 in the tank and they pick at each others tails all day. There is the occasional Danio chase against the guppies, but its really uncommon. Its mostly guppies chasing each other, they are really slow swimmers, inhibited by their massive tails which are now raggedy and torn up as you've seen. Some days it looks like fin rot, others day not at all.

I have this 20 gallon tank with:
4 assorted fancy guppies in the tank, 5 total (1 guppy became pineconed so I removed him to a qt tank where he still is)
6 zebra danio
1 BN pleco

45 gallon:
6 red irian rainbows
6 skirt tetras
6 panda corys
5 ottos

16 gallon:
20 cherry shrimp
3 Tuxedo koi guppies

The 20 gallon guppies have been a mess since I added them, especially the Tequila sunrises. One died right away. After a month, one grew bent out of shape and died very quickly. At first it was just fin rot on the guppies, so I tried to treat that but it never got better. Eventually some of the guppies began to grow bloated, develop stringy poop and passed away. Then the pleco's poop became stringy and I kicked into action. I got them from Petco, and did not quarantine them. I also saw white patches on the zebra danios, which have almost entirely cleared up. Still some residual white patches but they are breeding again which is a good sign. I've dosed Levamisole once and Prazi once.

The 45 gallon has been doing great up until last week. In an attempt to combat BBA, I dosed Seachem excel three days in a row. The rainbows lost all color and one developed a little white strip on his fin. I believe they have been infected with the tapeworms for some time, and the stress of Gluteraldhyde in the water was overwhelming for them. At this point I also noticed stringy poop from the rainbows, so this confirmed that Colin was right in suggesting I treat all tanks. I have done a round of Prazipro, no Levamisole yet. The 5 male rainbows are looking a bit better, but the female is having a rough time. She's not eating, hovering in place, and opening and closing her mouth repeatedly. The inside of her mouth has looked white, and I noticed a small raised white spot below her mouth. I am verging on treating for Columnaris before I run the Levamisole. Currently running carbon to clear out the Prazi, then I will make a decision on what to treat next. I will post a pic of the female rainbow in a few minutes.
'
The 16 gallon is doing okay. There is a very pregnant female guppy in the tank who has been growing more and more bloated, and she is now well past her pregnancy term. I fear the worms have made their way into this tank as well. That tank has been dosed with one round of Prazipro. Next I will do Levamisole. I've been advised to maybe not deworm pregnant guppies, but I don't think I have any other option. I don't think she will make it regardless. :(

Those are my current struggles. Sadly, none of the tanks are doing well now. Things are looking a bit better, but hard to say they are improving. I'll happily accept any advice, or consolation, lol.
 
Eh, the water hardness probably wasn't anything to do with the fin problem, hardwater fish kept in soft water suffer problems from the lack of minerals, it's more a long term problem that affects them internally, and shortens their lifespan. You wouldn't see visual evidence after just a few weeks in soft water. You're far from the only person who hasn't known about the importance of GH either, I kept otos (soft water fish) in my hard water for nine months, oblivious, since they seemed to be thriving, until I came here and learned about water hardness and the effects in has. I now have them in softer water, but I did lose three with no other obvious cause over the next few months. For soft water fish, the excess minerals in hard water build up internally, eventually causing internal damage like blocking their kidneys. There isn't anything you can see externally, they just pass away much sooner than they should.

For worms, you need the right meds, nothing else will get rid of them. But you have the right meds now :)

Hmm, I'm suspecting that this isn't 'fin rot'. I reckon the danios are shredding the guppies fins. I tried some guppies in a tank with some schools of tetra and zebra danios for a short while, and the guppies tails were shredded, just like the ones in your last posts. I don't know for sure whether it was the neons or danios, but I once I moved the guppies into a different tank, no danios or tetra, their tails healed up just fine. Had no issues with guppies in any of my other tanks, only in that one. It was other fish shredding them, not the water.

Sorry, it's hard to keep track since you have a bunch of different threads, but what's your complete stocking? What size tanks, with how many of what fish? Want to try to help you fix this, and it's better to rule out the simple things before throwing different meds at them for fin rot after treating the worms, only to discover later that it's not bacterial or water quality, but danios tearing their fins, or the male guppies ripping each others tails. Especially since you've been trying to battle this for six months and nothing has worked before... makes it even more likely that it's the danios or something else in the tank with them. Worms don't cause fin rot or torn shredded fins.

Oh I just saw your comment on my other post as well. Thanks, I am going to get a 75 gallon tank during the petco sale starting in November. Then I can move the 45 inhabitants to the 75, move the danios up to the 45 and leave the guppies in the 20. I also feel that the 20 is way too small for breeding Danios, they are so active and aren't even very small fish..... not sure why people say they can go in 10-20 gal tanks.
 
Oh I just saw your comment on my other post as well. Thanks, I am going to get a 75 gallon tank during the petco sale starting in November. Then I can move the 45 inhabitants to the 75, move the danios up to the 45 and leave the guppies in the 20. I also feel that the 20 is way too small for breeding Danios, they are so active and aren't even very small fish..... not sure why people say they can go in 10-20 gal tanks.
That's very good news! I have to feed my tanks and give my dog her training/play session now, but will come back later with some more suggestions, but this plan sounds awesome! Keep it up, I had a rough start too, lots of problems in my first year of fishkeeping, where it feels like you're cursed and have a lot of losses - I came close to giving up the hobby a few times, feeling like things kept going wrong despite all my effort and research - I felt like I was terrible at this and was a fish murderer.

But after properly treating everyone, and learning more and stepping up water quality and my routine, my tanks are thriving, fish are breeding, no one is sick... and the hobby is fun again. I don't feel awful and like I'm killing them anymore! It's rough when there are a few issues going on, and advice is so conflicting everywhere. But once they're treated and in the right tanks with the right amount of water changes, you'll reach the other side too! Keep your chin up, we all go through this rough patches and you've clearly thrown yourself into learning trying to fix things. This too shall pass!
 
That's very good news! I have to feed my tanks and give my dog her training/play session now, but will come back later with some more suggestions, but this plan sounds awesome! Keep it up, I had a rough start too, lots of problems in my first year of fishkeeping, where it feels like you're cursed and have a lot of losses - I came close to giving up the hobby a few times, feeling like things kept going wrong despite all my effort and research - I felt like I was terrible at this and was a fish murderer.

But after properly treating everyone, and learning more and stepping up water quality and my routine, my tanks are thriving, fish are breeding, no one is sick... and the hobby is fun again. I don't feel awful and like I'm killing them anymore! It's rough when there are a few issues going on, and advice is so conflicting everywhere. But once they're treated and in the right tanks with the right amount of water changes, you'll reach the other side too! Keep your chin up, we all go through this rough patches and you've clearly thrown yourself into learning trying to fix things. This too shall pass!

Update for this morning, the female rainbow has confirmed columnaris. I'm going to hold off on the levamisole treatment and address the columnaris now. I only have Maracyn and Maracyn 2 on hand, so I'll go with that. Better than to wait for 2-3 days for Kanaplex and Furan-2.
 
Update for this morning, the female rainbow has confirmed columnaris. I'm going to hold off on the levamisole treatment and address the columnaris now. I only have Maracyn and Maracyn 2 on hand, so I'll go with that. Better than to wait for 2-3 days for Kanaplex and Furan-2.
Rainbowfish don't normally get Columnaris. They do bump into things and get puffy white lips, this is bruising and goes away on its own. Some salt in their tank can help them heal up too.

Post some pictures and a short video if you have sick fish. Having people guess at diseases based on symptoms is a good way to get an incorrect diagnosis.
 

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