55 Gallon Community Compatibility

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NotNowChief

Aquarium Advice Newbie
Joined
May 28, 2014
Messages
8
Location
New York City Area
Hi all,

I've been reading these forums for quite some time, and finally decided to join in and ask some questions, and maybe answer a few from my experience. I've had various tanks in various configurations over my 35 years of age, mostly keeping larger fish, and recently decided to venture into taking an exisiting 55 gallon aquarium and putting together a community with many small fish, and one big guy who needed to keep his home.

I also have a 15 gallon column aquarium with a Fluval 206 (currently fishless cycling) and a 5.5 gallon quarantine/isolation tank I maintain with cycled filter media for any issues that may arise, as described below.

First, let me start with the "big guy", a common Pleco about 8-10 inches long. His tankmate of 9 years passed away recently (the Jack Dempsey in my profile picture, also kept for 9 years, and he was BIG) and needed some companionship. I wanted to keep him in the big tank so he had the room he needs, and after consulting with friends and some other sources online, I decided to leave him be and add some small tankmates. Yes, there were some stories about Plecos going after small tankmates, but after 9 years of seeing him be incredibly docile, I figured it was worth the gamble.

For the tankmates for my large Pleco, I have 5 Red Eye Tetras, 3 Candy Cane Tetras, 5 Cory Catfish, 2 Dalmatian Mollies, 2 Butterfly Lyretail Mollies, and 9 Neon Tetras.

Everything was fine for 2 months. Water is/was fully cycled, running 2 Aquaclear 70s, a 200 watt heater, temperature at 78 degrees, 0 Ammonia, 0 Nitirites, 0 Nitrates as I do a 10 gallon weekly water change using Aqueon Water Conditioner to pretreat the water as our tap water is chlorinated.

My issue lies with my Neons getting picked off one by one.

Of course my first thought was the Pleco, but I was skeptical since after keeping him for 9 years I have seen his temperment. So I began Googling. Contrary to what I was told, the Mollies, especially the Dalmatians are quite nippy. I have observed one of them being very nasty at feeding time. Once I found 3 neons missing, I decided to put the 2 Dalmatians in my 5.5 gallon quarantine/Isolation tank that I keep running with cycled filter media in case this happened. Within 2 days, one of the Butterfly Lyretails became the dominant one in the 55 gallon tank, and started nipping more neons. Each morning I would find another dead Neon stuck to one of the filter intakes.

So last night I took the 2 Butterfly Lyretail Mollies out and stuck them in the 5.5 gallon tank with the 2 Dalmatians, and this morning, 2 more Neons were gone.

So, are the Red Eyes or Candy Canes thinking the Neons are food? The Pleco? The Cories? I am skeptical to blame the Pleco because I am finding bodies, from what I understand they would just eat the Neons whole, especially since he's a big dude. All the Neons I have pulled off the filter intakes have heavily nipped rear fins. I have observed the Mollies nipping but no one else.

No other fish are getting picked on besides the Neons.

Should I take the Neons out and put the Mollies back in and see what happens tonight? I feel like this is an aquatic version of Clue!

Comments and feedback are welcomed!
 
If it's not the mollies, my guess would be the red eyes. They are fairly nippy fish.

Are you sure your nitrates are at 0? In a cycled tank, there should be some level of nitrate. Also, a common pleco is going to need a bigger tank. They get massive and are total poop machines. A common recommendation for them is 125g+.
 
I've seen red eye tetras act very aggressively. I've also seen neon tetras become aggressive to each other. How long have you had them.
 
Yep, I use the API Master Test Kit, no test solutions are expired, it always reads clean. 1/5 water change every week, a small-moderate bioload, and 3 bags of BioMax in each of 2 AQ70s.

I understand the life span of common Plecos, when he needs a bigger tank, he'll get one. By then I'm sure my basement will be finished and I'll be able to to have a large tank downstairs. he enjoys his vegetables and algae disks in the meantime and makes a wonderful "centerpiece" with all the little guys in there. Quite a surprise when he's spotted in there by houseguests.

I appreciate the feedback, which is why I'm just considering removing the Neons and putting the Mollies back and then seeing what happens, they were the last added and never had this problem before adding them.
 
In some cases tetras will fight to establish pecking order but I've never heard of it going this far.
 
Is this tank heavily planted? If not I don't see how you can have no nitrates either.

Sent from my SGH-I747M using Aquarium Advice mobile app
 
I tested nitrates again last night and it was barely orange on the API chart, right around 5PPM. However, I am not sure what the correlation is about low nitrate levels after a water change and fish getting eaten. But to appease the gods, so be it.

I reintroduced the 4 mollies yesterday afternoon, and removed my remaining 5 neons into my spare tank, and all seemed fine this morning.

I guess it may have been the Red Eye tetras after all.

So.......with my large Pleco, 5 Red Eye Tetras, 3 Candy Cane Tetras, 5 Cory Catfish, 2 Dalmatian Mollies, and 2 Butterfly Lyretail Mollies, what else can I add without worrying: a few more Candy Cane Tetras or a few more Red Eye Tetras? I really like to add a few more of something. Ideas?
 
I tested nitrates again last night and it was barely orange on the API chart, right around 5PPM. However, I am not sure what the correlation is about low nitrate levels after a water change and fish getting eaten. But to appease the gods, so be it.

I reintroduced the 4 mollies yesterday afternoon, and removed my remaining 5 neons into my spare tank, and all seemed fine this morning.

I guess it may have been the Red Eye tetras after all.

So.......with my large Pleco, 5 Red Eye Tetras, 3 Candy Cane Tetras, 5 Cory Catfish, 2 Dalmatian Mollies, and 2 Butterfly Lyretail Mollies, what else can I add without worrying: a few more Candy Cane Tetras or a few more Red Eye Tetras? I really like to add a few more of something. Ideas?

The nitrates really didn't have to do with the killed fish, it was just an oddity I questioned since it's not normal for a tank to have 0 NO3.

As for stocking, the pleco still is going to need a new home - but past that, you could definitely add some more red eyes and candy canes. You could probably add some more corys as well.
 
Oh I appreciate the input, I never thought much of the very low Nitrates because of the 1/5th water changes per week with gravel vacuuming, and I have alot of small fish.

Just last night I tested again because you guys had me doubting myself, 0 Ammonia, 0 Nitrites, and negligible amount of Nitrates.
 
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