Pleco Problems

Question
Hi there Nicole, and Happy New Year!

I have some problems with the two plecos I keep in my 35 gallon aquarium. I noticed my plecos have some tearing and pieces missing in their fins, but I see no evidence of fungus on their fins. No discoloration or odd texture on the torn looking edges of their fins. Do you know what might cause that? Their tankmates are 2 guppies, 1 molly, 3 danios. There are a total of 8 fish in the tank. The plecos are about 4" long, and 1 is a common while the other is a bushy nosed.

Also, my plecos have not been fighting eachother as far as I can tell. They seem to be friends. No other fish are harassing them (at least not during the day and when i have the light on).

Can you give me any advice? An aquarium salt dip perhaps?

Here is a picture of where the tears are occuring:
http://www.geocities.com/anna_fritschi/plecoprob.bmp

The red lines indicate where the tears are in my plecos' fins.

Answer
Hi Anna,

Well, it's hard to say exactly what is wrong here. I have some ideas, but none of these might be the case.

Scenario #1: water quality issues. Fish like bettas with long, flowing, paper thin fins are especially prone to fins becoming torn because of water quality. The pH dropping sharply, the water getting stale from not being changed enough - bettas with torn fins are not uncommon. Sometimes they even chase their tails, especially if they're bored. However, plecos are very tough fish, whereas mollies are not, so if anyone had water quality related issues, it would probably be the mollies to show first of all.

Still, it doesn't hurt to check. Make sure you have 0 ppm of ammonia and nitrites, which you can check with a water test kit. Nitrates should be kept as low as possible, levels above 20 ppm can begin to become problematic. Also, make sure your pH is not dipping sharply. An aquarium always has water more acidic than the straight tap, but make sure it is not a huge difference. pH is based on an algorithm of 10, so 1 point difference is 100x! a pH of 6 is 100x more acidic than a pH of 7, etc. It's important in fishkeeping to ensure the pH stays stable, and this is where alkalinity comes into play. Hopefully your test kit doesn't say you have "low alkalinity" because this means your pH is liable to bounce around, and you'll need to do frequent water changes to keep the pH stable. Moderate to high alkalinity often makes for much easier fishkeeping, although some fish object to alkaline water - advanced fish like dwarf Apistogramma cichlids, etc. In general, hard water is a blessing!

Scenario #2: sharp decor. Make sure you don't have plastic plants that are exceedingly sharp or any kind of sharp gravel like glass gravel chips (hopefully out of vogue by now). Also, make sure there is not any point decor such as sharp fake or real coral skeletons. These will hurt your fish, especially fish that stay on the bottom as plecos do.

Scenario #3: fighting. Plecos are actually rather territorial. One to a tank is best, unless you have a really large tank with lots of caves and driftwood for territory spots. Plecos can do territorial things like chase each other in circles, and while their "sucker" seems harmless, they can actually make welts with it, so do keep an eye out! Since plecos are nocturnal, you'll have to watch with a flashlight at night when they're active.

Your common pleco will outgrow your 35 gallon aquarium within a year or so, so it's a good idea to start thinking of rehoming him anyhow - the bristlenose is a perfect size for your tank. I have one in my 29 gallon tank, too, and had a common pleco at one time in there. He eventually outgrew the 75 gallon tank he got rehomed to, believe it or not!

And lastly, Scenario #5: nutritional deficiency. Plecos need driftwood in their diet, it helps their digestion, so get at least a small piece of driftwood for them to graze on. These "wood chippings" do more than just add fiber to the diet, it seems, since plecos are not as healthy in tanks without wood. Odd but true! Also, they can't just scavenge food as some pet stores purport, they need their own meals. Algae wafers and fresh vegetables supply their nutritional needs nicely. Mine love cucumber and zucchini, or yellow squash. They will also graze on lettuce and spinach. They eat a little bit of sweet potato, but they don't love it. You can just cut a slice (blanching it in the microwave for a few seconds if you choose) and weigh it down with a magnetic Chip Clip or other heavy clip, then remove it when it starts to get soggy and falls apart. Your plecos will sure appreciate having some fresh veggies a few times a week!

In any case, not sure if this will give you much insight, but I hope it helps. Take care, and happy new year!

Nicole

P.S. Skip the salt dip - plecos do not like salt. If the tears start to wear away or become fluffy or cottony, then you need to treat them (or the tank) with a fungus/finrot remedy - many medications will treat both at once. However, on a healthy fish, frayed fins regenerate rapidly without any intervention needed. You could try some Melafix if you wish, but this very mild "medication" doesn't do much, especially not when advanced symptoms appear. However, as a pre-emptive strike, Melafix or Stress Coat might help!