Concern in my 75g “community” tank

Hello all,

So I have a 75 gallon tank which currently houses
1 red spotted severum
1 EBA
1 Synodontis catfish
3 Rainbows (2 passes away recently)
6 polar blue parrot convict cichlids

So I did have a group of 5 rainbow fish, but now it is down to 3. I checked the water, and it had perfect readings. I do weekly water changes of about 40% because of the cichlids, the syno is amazing at getting all the extra food though so my nitrate is never about 0. I have no clue as to why they died, I’ve only had them for about a year as the rainbows were the last edition to my tank. The one rainbow had lymphocytis since the beginning I figured that’s why it died until another died a few weeks after (2 days ago). I’ve been watching the tank the last half hour, and I noticed that one of the rainbow fish does not group with the other two. He just sits off on his own, but he doesn’t seem lethargic or any signs of sickness. Another thing I noticed is if they get to close to 3 of the bigger PB cichlids, they chase them a little (half a second to get them away), which before I haven’t noticed when I first got them. My theory is that the PB stressed out the last one so much that it died, but they do not pursue the rainbow fish or target them, only if the rainbow fish get close to them they give them a little aggression to back away. Any advice on what I should do? Currently the 3 options I am thinking is to:

1) Try to add more tall plants to break up the tank more as the middle open so my severum has a lot of open room to swim, but I don’t think that will change much
2) Remove the 3 larger PB cichlids, but I think that the smaller ones will then just rise up to take their place, but the smaller ones for example never go after any fish. I also do love them
3) Rehome the rainbow fish and attempt to introduce something else. Only issue is I have no clue what to add as I cannot add any larger fish. I’ve tried options before I had the PB and rainbow fish like rainbow cichlids, more acaras, geophagus, gouramis, but none of them did well.

Or last option is to bring back up the rainbow fish numbers to 5/6 to see if it will help and Maybe remove the most aggressive PB and rearrange the tank so they create new “sections” for them.

Thoughts?

Pictures and video of the fish?

What does the fish's poop look like?
Are they eating well?
Do they get fat overnight just before they die?
Do they sit near the surface or filter outlet just before they die?
Do they stop eating before they die?

Why do you have 6 convict cichlids in the tank?
They are highly territorial and when they start breeding, they will wreak havoc in the tank.

Those are all big messy fish are you 100% you dont have any nitrates week to week? Which test kit are you using? Is the tank heavily planted? I'd have thought the Severum might have something to say about that haha...

When you say one of the Rainbows had Lymphocytis are you 100% on that, sores on the body (and I imagine this is what Colin is thinking) could be fish TB which is brutally prevalent with Rainbow Fish.

@Colin_T the Polar Parrot Convicts are a hybrid, they are not meant to be as aggressive as natural convicts and they usually have the deformed mouth of a parrot fish so can't do too much damage.

Wills

Wills said:

Those are all big messy fish are you 100% you dont have any nitrates week to week? Which test kit are you using? Is the tank heavily planted? I'd have thought the Severum might have something to say about that haha...

When you say one of the Rainbows had Lymphocytis are you 100% on that, sores on the body (and I imagine this is what Colin is thinking) could be fish TB which is brutally prevalent with Rainbow Fish.

@Colin_T the Polar Parrot Convicts are a hybrid, they are not meant to be as aggressive as natural convicts and they usually have the deformed mouth of a parrot fish so can't do too much damage.

Wills

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i do not think it was TB as not if the other fish have it. It wasnt a sore but looked more like a white lump on her body. I have I’ll put a stock image of what it looked like. The severum is very peaceful and so is the EBA. The PB do not dare go near them or the syno. The rainbows also do not have any marks either so that is why I am curious as to what happened to the most recent one. The tank has no plants, but also none of the fish besides the syno are full grown, but anytime I test Nitrate it is also 0 I use the API master kit.

Colin_T said:

Pictures and video of the fish?

What does the fish's poop look like?
Are they eating well?
Do they get fat overnight just before they die?
Do they sit near the surface or filter outlet just before they die?
Do they stop eating before they die?

Why do you have 6 convict cichlids in the tank?
They are highly territorial and when they start breeding, they will wreak havoc in the tank.

Click to expand...

I’ll post some videos and pictures of the fish later today as I have a symposium this morning I am headed to. The fish eat well, there’s no white poop that I noticed. They also do not look fat or get fat overnight when the last one died. They do not go near the surface or near the filter as the one that is by himself is usually just mid level on the side of the tank. They all ate well from what I could tell but I will keep a close eye when I feel they tonight. Also, they are note pure convicts but are hybrids of convict/parrots I put a picture of one each that I had in my phone of the biggest one, they are half as small as the rainbows

Don't add anything to the tank until we work out what is going on otherwise you could be making things worse.

The fish in the picture look fine and they don't have the signs of Fish TB when they die, so that's good.

The rainbowfish didn't die from stress due to the cichlids.

I am amazed the nitrate is 0ppm all the time. Are you sure about that? Nitrate test kits can be funny if you don't shake them properly or add the reagents in the correct order.

How often do you clean the substrate?
Do you dechlorinate the new water before adding it to the tank?
Do you have buckets and hoses specifically for the fish tank?

What sort of filter is on the tank?
How often and how do you clean the filter?

What do you feed the fish and how often do you feed them?
Do the rainbows get any plant matter in their diet?

Colin_T said:

Don't add anything to the tank until we work out what is going on otherwise you could be making things worse.

The fish in the picture look fine and they don't have the signs of Fish TB when they die, so that's good.

The rainbowfish didn't die from stress due to the cichlids.

I am amazed the nitrate is 0ppm all the time. Are you sure about that? Nitrate test kits can be funny if you don't shake them properly or add the reagents in the correct order.

How often do you clean the substrate?
Do you dechlorinate the new water before adding it to the tank?
Do you have buckets and hoses specifically for the fish tank?

What sort of filter is on the tank?
How often and how do you clean the filter?

What do you feed the fish and how often do you feed them?
Do the rainbows get any plant matter in their diet?

Click to expand...

I agree I haven’t added anything as of yet hence why I came here first. That picture of the rainbow fish isn’t the one that had lymphocytis but the stock image I put resembles the bump she had on the side of her body for the year I had her.

1) For the tests I do shake every bottle and put them in order 1 then 2
2) I clean the substrate weekly with a 40% water change.
3) I dechlorinate using “Prime water conditioner any new water.
4) Yes for each of my 2 tanks I have a separate syphon and bucket
5) I have a Aquaclear 110 that I run with 2 foam layers and 1 bio layer (no carbon except for medications which I haven’t used in a few years besides melafix was the last one I used a few months ago
6) I clean the filter about every 1-2 months using only dechlorinated water/ tank water.
7) I feed the fish every other day and feed them a combination of omega cichlid pellets and also these veggie waffer/ pellets. Plant wise I do not feed them any actual plants if that’s what you mean

I used to keep duckweed in all my rainbowfish tanks and the fish grazed on that throughout the day. They need a lot of plant matter in their diet.

Lymphocystis should not last a year unless the fish is really stressed out and if they are stressed for a year, they usually die during that time. Normally it disappears by itself after the fish have settles down, and it only takes a month or so to go.

At this stage I would say monitor the fish for aggression and unusual behaviour. Film and photograph anything that doesn't look right and pop it on here asap. Hopefully we will be able to work out what's going on.

Colin_T said:

I used to keep duckweed in all my rainbowfish tanks and the fish grazed on that throughout the day. They need a lot of plant matter in their diet.

Lymphocystis should not last a year unless the fish is really stressed out and if they are stressed for a year, they usually die during that time. Normally it disappears by itself after the fish have settles down, and it only takes a month or so to go.

At this stage I would say monitor the fish for aggression and unusual behaviour. Film and photograph anything that doesn't look right and pop it on here asap. Hopefully we will be able to work out what's going on.

Click to expand...

I could add some duckweed to the tank I’m afraid the severum will just tear it up but if it’ll help the rainbows I can definitely look into it. But I’ll update it is pretty much how it was yesterday, I don’t see much aggression but the one rainbow is just by himself

The aggression was more towards the cichlids having a go at the rainbow.

The severum should have plant matter in its diet too.

Colin_T said:

I used to keep duckweed in all my rainbowfish tanks and the fish grazed on that throughout the day. They need a lot of plant matter in their diet.

Lymphocystis should not last a year unless the fish is really stressed out and if they are stressed for a year, they usually die during that time. Normally it disappears by itself after the fish have settles down, and it only takes a month or so to go.

At this stage I would say monitor the fish for aggression and unusual behaviour. Film and photograph anything that doesn't look right and pop it on here asap. Hopefully we will be able to work out what's going on.

Click to expand...

Hey @Colin_T,

So I have been watching the tank at random points in the day, no abnormal behavior besides as I mentioned earlier the one Rainbowfish is on his own while the other 2 are together. The one that is on his own does have nip marks on his fin, I am not sure if that is from the PB or from the other rainbow. I did see the when the two rainbows (orange ones) were closer, they were side by side and would do some type of dance almost. Apart from that, I’m about to clean my tank like I do weekly and here are the measurements

Temp: 75
Ammonia: .05
Nitrate: 0
Nitrite: 0

These measurements are 1 week since I last cleaned it and will be doing my normal water change. I plan on leaving my phone in the room and recording a 10 minute video later today so you can also observe how the tank normally is.

Stefan3289 said:

Hey @Colin_T,

So I have been watching the tank at random points in the day, no abnormal behavior besides as I mentioned earlier the one Rainbowfish is on his own while the other 2 are together. The one that is on his own does have nip marks on his fin, I am not sure if that is from the PB or from the other rainbow. I did see the when the two rainbows (orange ones) were closer, they were side by side and would do some type of dance almost. Apart from that, I’m about to clean my tank like I do weekly and here are the measurements

Temp: 75
Ammonia: .05
Nitrate: 0
Nitrite: 0

These measurements are 1 week since I last cleaned it and will be doing my normal water change. I plan on leaving my phone in the room and recording a 10 minute video later today so you can also observe how the tank normally is.

Click to expand...

Update while cleaning the tank, so in total I have 3 rainbowfish currently, 2 orange (boses) and 1 blue. The one orange one lingers by himself and has no marks, but the orange and blue that travel together, I see that the blue one nips the orange ones fins and he has noticable fin nips. The other 2 ones that died were also orange (boses). Could the blue rainbow be the aggressor and have eventually killed the other 2?

Rainbowfish don't kill each other. They show off/ display to each other and sometimes the fins might split or get slightly damaged, but as a general rule they don't harm each other. About the only exception to this is big male Glossolepis incisus that can bully and occasionally kill smaller males or females. This usually happens when there is only one big male G. incisus and a couple of smaller fish. I have never had it happen in my tanks, but my tanks always had 10-30 rainbows in and they were all similar sized. Other people have reported it and it was when they had a 4-5 inch male G. incisus and a couple of 2-3 inch fish with it. The males get territorial and bully smaller males until the weaker fish dies. It doesn't happen in the wild due to numbers and fish being the same sized, as well as having heaps of space to swim away from any aggressor.

Colin_T said:

Rainbowfish don't kill each other. They show off/ display to each other and sometimes the fins might split or get slightly damaged, but as a general rule they don't harm each other. About the only exception to this is big male Glossolepis incisus that can bully and occasionally kill smaller males or females. This usually happens when there is only one big male G. incisus and a couple of smaller fish. I have never had it happen in my tanks, but my tanks always had 10-30 rainbows in and they were all similar sized. Other people have reported it and it was when they had a 4-5 inch male G. incisus and a couple of 2-3 inch fish with it. The males get territorial and bully smaller males until the weaker fish dies. It doesn't happen in the wild due to numbers and fish being the same sized, as well as having heaps of space to swim away from any aggressor.

Click to expand...

I see what you mean, but the one rainbow had quite the amount of damage to its fin, it was getting pretty close to the base of his tail and that blue rainbow one was the only one that was nipping him like that. The blue one would chase him around and when the orange one let his guard down, he would bite his fins. The other orange one that was more by himself and blue one had no marks on the fins, which leads me to the believe that the PB were not the ones at fault but rather the blue rainbow

If you can get a video of them biting, upload it to YouTube, then copy & paste the link here.