Bristlenose woes

About 3 months ago I got 8 1.75" ( and a .75" "bonus") bristlenoses from a local breeder. All went into a 20H as QT with a few juvie platies.

My intent was to move them into my other tanks once I had enough driftwood for the other tanks....realizing that they couldnt all stay there forever. I saw some minor squabbling over space, but nothing major.

A month later, I counted 7 while cleaning the tank. I chalked it up to transportation/acclimation stress and didnt think much of it. Water normal, 0-0-20, doing ~60% WC's every few weeks.

Two weeks ago I found one dead; it had been over 3 weeks since a WC, nitrates were between 40-80 Didn't realize they were such prodigious producers of poop. Final count was 4 (now 2") plecos left; also lost 2 platies that were kinda weak to start with. Did 2 ~60% WCs over the next two days.

Figured I'd let the 'trates get too high and would make sure to keep up on the WCs. Thought about dispersing them to different tanks, but had no driftwood ready(still soaking). Apparently I should have done it anyway:

Been away for two weeks; came back yesterday to find only two bristlenoses left and 1 juvie platy dead. Found no dead plecos, so they must have been gone for a few days. Nitrate at 20, did a 60% WC, probly will do another tomorrow.

Water params before WC yesterday:
pH 7.6 (my tap water is ~7.8)
Ammonia just over 0 (clear if 0, had a very slight tint of yellow)
Nitrites 0
Nitrates 20
<shoulda checked phosphates but didn't>
Temp~ 79F

Tank is a 20H lightly planted with a 15W tube; 100W submersible juwel heater, RUGF with one Penguin 660r powerhead & a Whisper 20 HOB (no carbon). I use tap water with Prime, I dose for the whole 20H then fill with water close to tank temp. MTS, small ramshorns and pond snails in tank too. The 20H above it has 2 corys and 50+ Endler's...similar setup and it's just fine.

So...
I understand losing some when the nitrates were high, but now? I'm down to 2 2" plecs and 5 juvie platys in a 20H...bioload should not be an issue.

-I'm losing the occasional platy; this suggests a whole tank problem...but the platies were stressed to start with tho...
-I'm thinking about adding some ammo-carb to remove anything wierd that I can't test for...and the ammonia being anything but totally 0 bugs me.
-At ~2" are bristlenoses aggressive/territorial enough that they might just be beating the crap out of each other when I'm not looking? The two dead I saw a few weeks ago looked fine, maybe a little chubby in the belly, but no obvious physical damage. (internal infection?)
-Getting burned on the heater? Doesnt seem THAT hot to me...
-79 too warm?
-???

Closer inspection shows that two of the platies have very long stringy 'poo', and several of them are lethargic. Looks like I need to treat for internal parasites...

This tank is on the bottom of a 2-tank stand...nearly at floor level...if it had been the top tank, I probably would have noticed that sooner...arrgh....

wataugachicken said:

have you checked inside the whisper and all around/under the tank? i have that filter and occasionally one of my bn's will try to get inside it. while trying to get into a filter, sometimes they go the wrong way and end up on the floor.

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...you mean, "Did I interrogate the cats?" any fish on the ground would quickly be cleaned up. interesting thought tho...maybe why some are just plain missing. Two did definitley die in the tank tho.

wataugachicken said:

otherwise, i think that the large irregular water changes could be a contributing factor, similar to old tank syndrome.

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Could be...certainly not helping. normally I never let it go more than 3 weeks, typically two weeks.

wataugachicken said:

as far as the aggression, in my experience they are not that aggressive. bn's that are kept together get along just fine. if you separate them for a while and then reintroduce them they will have little battles over the best hiding spots, but they settle down in a matter of days. however, if you don't have any hiding places them they might be fighting.

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at least 5-6 good hiding spots, plus plenty of room on the driftwood and filters. The squabbles I saw looked more like the ones I see btwn my cats....a swat and a snarl and it's over.

toddnbecka said:

Pleco's are more sensitive to water quality, need more frequent partials. Proper diet is another important factor.

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Im going to have to start doing a WC every week I think, even if it's just a WC and not a vac job.

Food-wise, they are getting:
Aquadine duradisks (fish/wheat/shrimp/soy/spirulina) primarily
Omega One Veggie Rounds (kelp/spirulina/fish) occasionally
and surprisingly, they LOVE Omega one goldfish sinking pellets (Fish/Shrimp/Wheat/kelp) once in a while as a treat...

wataugachicken said:

if you choose to tear the tank apart looking for them, i am pretty sure that you would at least find a few skulls if they died in the tank. those would last a lot longer than a body. otherwise, they probably jumped out.

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good point...I didn't find any skulls, but I wasn't looking for 'em either.

Maybe I need to devise a way to cover the filter so they can't get out.