Plecos keep dying :(

[mickitiffen]

I have a 20 gallon tank
2 albino cat fish
1 ghost knife
2 gouramis
1 snail
live plants

Water parameters have tested normal, no ammonia present, nitrites(3), nitrate(40), ph, kh/gh are high(180 or so-but I have been told this is not a problem.

I have cleaned out the Eheim filter and replaced the pad last week, cleaned the Eheim prefilter and treated the tank with Amquel. Usually I do 1 large water change a month but last week I did 2 including vacuuming the gravel on the last one.

I had a large Pleco who died and over the past month I have replaced it with 3 more Plecos and each time they live about 3 days and then die. The 3 that died all came from the same store. Before they die they seem to be not doing much, just hanging on the tank, but then again I assume that is common behavior.

I had a lot of algae but gave the Pleco a wafer as well. Some of the algae seems red. I have been cleaning it out.

All the other fish are acting normal and seem fine.

I am perplexed. Any suggestions?

[dudeofrude]

I wouldn't say that 'just hanging on the tank' for 3 days is common behavior? Young plecs are usually very active and like to discover the tank, its as they age and grow they become more docile and dormant. Id point my finger at the aquatic store, have you contacted them about it??

[mickitiffen]

It was active at first. I have told the store when I replaced each of them and they had nothing to say really as any help. If it was something at the bottom one would think it would affect the cory cat fish as well.

[Tim Wheatley]

That algae is probably brown not red. Search diatoms on the forum.

My young pleco isn't too active with the lights on, but very active at night. Have you watched him then?

[mfdrookie516]

3ppm nitrites are killing your fish, whether it's having an effect on your plecos is to be determined. how are you acclimating them? if it were 1 fish, you could probably blame it on the store having bad stock... 2 fish is up in the air... 3 fish says you're doing something wrong.

[mickitiffen]

At this point I have no pleco's to watch unfortunately. I am just trying to solve for why they are dying on me.

[mickitiffen]

Why is it not killing the cory catfish or other fish in the tank then?

[mfdrookie516]

It is killing them, they just haven't died yet. Nitrite is extremely toxic to fish. You should be doing lots of water changes until it gets to 0ppm and stays there.

[mickitiffen]

What frequency do you recommend? 1x a day? I am using Amquel as well as that is supposed to reduce it. When I had a problem about 2 years ago someone recommended putting in more than the recommended does of 1 tsp per 10 gallons. Any recos on that?

[mfdrookie516]

Cant say about amquel, I only use prime. I would recommend back to back water changes until the nitrite is below .5ppm, then as needed any time it gets above .5ppm

[mickitiffen]

what exactly do you mean by back to back water changes. Daily? I am also thinking maybe I emptied too much of the old water from the filter. I removed most of it when I cleaned it on Monday. The Eheim filter pad was pretty murky and all the water in the cannister looked brown--I left some in but maybe I took out too much.

[mfdrookie516]

i mean do a 50% water change now, then when you get done, do another one, then when you get done, do another one... test your nitrite... it should be about .4ppm if you do 50% each time... then monitor it several times a day and do a 50% pwc any time it gets above .5ppm

[mickitiffen]

Change water all day long? I have heard that can really stress the fish. I stopped in at the fish store and tested the water.They said the ph is too low(6) so I used 2 tabs of ph adjuster--not much change after 12 hours. I also added carbon to the filter per their reco (my late husband did not use it --his tank). Any thoughts?

[Tim Wheatley]

If the water is dechlorinated first it shouldn't have any bad effect except perhaps killing some of the bacteria in the filter. It will be preferential to the water before the water change. Just try to match the temp of the water going in with the water coming out.

I wouldn't use pH adjuster, ever. I'd be more likely to advise you to use natural means to alter pH such as driftwoods/limestones. Plecos originate from acidic water (low pH) anyway so I'm not sure why they would have said that. Anything from the Amazon (where the rotting debris of the amazon rainforest makes the water very acidic) should be very capable of living with a 6.0 pH. It's more important to give the Pleco plenty of oxygen in the water than a perfect pH in my opinion.

Have you used those pH adjusters before? They can cause quite drastic and sudden changes in pH that do more harm to the fish than anything else I've ever encountered. If you've used them a lot that could be your problem in the tank. The pH adjusters change the pH until they burn out and are gone, then the pH drastically swings back to where it would be without them. Often this sudden change can kill.

[mickitiffen]

I tried the pH adjuster after the death, but there was no effect. Just did another water change, added charcoal to the filter last night, continuing to treat with AmQuel on each change. I always use a dechlorinator. The tank has coral in it and driftwood.

[Tim Wheatley]

Real dead coral is going to raise pH and driftwood probably can't overpower it. Is it possible your tap water is low pH? Can you test it?

I'm going to guess that your tap water is low pH and after your water changes the tank then raises pH, when you do water changes it then probably drastically drops it again. Just a guess, but can you test your tap water to see?

[Trout11B]

I'm new to the aquarium, fish raising hobby, but aren't your nitrates a little high also. Don't you want to have them below 20ppm, and you only really want them that high if it's a planted tank? Sorry bout your Plecs...

[Tim Wheatley]

Yeah they are. That's why mfd was advising water changes.

[mickitiffen]

I will test the tap water. I believe it is hard water from the city, so yes, you are probably right. I have been doing water changes 1/x day but think doing it all day long is drastic.

[Tim Wheatley]

I think he's just saying to do it until you get down to a better level, then you can go back to lesser changes.