Albino corys fin problem

I have some albino corys with fin rot.

I treated them with melafix so far. This is day 5 after dosing for 3 days straight. 2 days without now.

The tank is the one in my sig, if that'll help any.

tank:
55g / 48" long.

Plants - some.

Fish -
9 - albino corys
3 - swartz corys
2 - flame tetras
1 - guppy
8 - harleys
6 - otos (? lost count)
20 - neons
6 - ramshorns (noticable ones)

ammonia/nitrite - 0
nitrate - 20
pH around 7.3
KH around 4

was running DIY CO2. Just took it out today.

Been consistant with around a 29g WC, every week.

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3 albino corys and the swartzs have been in the tank before I changed it over to plants. They're a few years old. 3+? IDK. Been there a while.

I hadn't paid much attention to this tank until right before changing it over. Its my moms, but I'd do water changes n stuff for her.
I'd been working out of town for a few yrs during the week. And see the tank long enough to change water, and see what fish I'd see where doing ok.

But when I went to change it over, we moved out most of the fish that where in it. Everything but the 2 flames and the six corys.
(Fish that were moved out... 2 clown loaches/upside down cat/6 balas)

This is when I saw the messed up looking albinos. Poor things looked all anorexic(sp?). But the swartz looked perfectly fine.

They were missing most of their fins. I remember one having one side of his whiskers gone. The others were at least, short.

They started coming back around real nice. Except for one, I guess he was too far gone. That would have been the fourth albino, all together.

All there whiskers had grown back nicely with in a week or two. All fatened up real good, etc. Except for fins.

I figured some of the fins where too far gone to come back. But they seemed to be doing good in general.

Then I added 6 more, real small albinos. They've been growing good, and almost the size of the older ones now.

The tank has an auto feeder that feeds every 4 hrs. I had it on every 3 hrs for a while. But changed it to 4 hrs a few weeks ago.


The problem is...
My newer corys have a little fin rot here n there.

What ta do, what ta do?
What causes it?

Thanks for the replys.

I done some searching around, right after posting this thread. And found what I thought... water quality problem.
After scratching my head on this for a day or so. Because dirty substrate, lack of water changes etc. Was unbeieveable from my stand point.
It gets gravel vac'd and around a 20g wc every week. And it hasn't been set up all that long.
Never saw ammonia or nitrite after the change over, sense the bio load was cut by around 80%. And was still using the bio-wheels with the 350 magnum. Plus, a tankful of plants.

Without going into all the how come, why for nots...

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Im now thinking "low oxygen lvls" could be the main culprit?

If so, couldn't this affect how things are getting broken down?

As in, a small amount of detritus could then be a big problem.

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The one big reason why I'm leaning towards this assumption. Is the fact that I haven't done alot for water movement compared to my past plain 'ol plastic plants fake tanks.

I am now, sense the 350 is back to running like a typical 350. Not that the way it was running was bad, I just need something else moving the surface better.

pinkertd said:

Yes, it's usually declining water quality and barbel erosion from substrate that's not kept clean enough. Why are you feeding them automatically every 4 hours? That's wayyyyyyyyyyyy too muich feeding. If they are almost full grown twice a day at most, once would be fine.

Click to expand...

The babels are doing fine. And have all grown back on the older corys.

Its not all that much food going in really.
Depending on the "feeder" on a given feed. It gives out about 20-30 pieces of food.
These things... > http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+7927+12814&pcatid=12814

Just a quick, ruff estimate. They're less than half the width of a dime.
A neon could easily eat 3, and would probably eat 6 or 7 if given a chance.

right now there are 20 neons, 2- flame tetras, 12 corys, 1 guppy, 8 harleys. uhhh forgot how many and not easy to count in there, but... otos 6-9?

And I guess they're not as big as I was thinking. I just saw a small one right next to my biggest, older one. And he was only about half its size.
I'll try to get some pics. I tried before but can't seem to get very good oictures of anything.



Thanks for the replys, and keep the ideas comming.

I got a couple of pics to turn out not soooo blury...
The pic might get bigger if you click it? Usually does for me.

The little guy in the front...
Nice fumanchu going on, as are ALL of the corys now.
What gets me, is the fins!
It almost looks like they're bittin off or something? Is this the typical look of fin rot?



Heres a pic of my older, worst condition one.
I felt so bad when I finally noticed these guys. There was one worse than him, that died about a week after the change over.
The poor guys were as skinny as could be, with hardly no fins.
I assumed his fins have/are grown back as good as they're going to get. Sense they were so far gone.

As you can see they've fattened up real good. Have nice long, clean barbels, etc.



So...

Any thoughts on the(the previously mentioned) Low Oxygen lvl, being a culprit?