I Am Devastated! Dead Bolivians....more Unhealthy Fish Also

[LoachLover!]

I have been a bit unsure as to what has been going on in my tank lately.  I haven't added any new fish since the end of December, when I added another angelfish and a Pearl gourami to my 55 gallon aquarium.
 
My tank has been set up for over a year, and for the most part has been good and I have had nothing but the odd isolated fish illness or death.
 
About a month ago, I noticed that one of my three bristlenose plecos (two are juveniles and I am hoping one will be a male for breeding purposes) started acting weird.  She would sit in the same spot for hours on end and not move a muscle, no matter what was going on the outside or inside of the tank.  She had been a very greedy fish and a moody one also and no fish went near her algae wafers.  But, for the last month or so, she has not touched a single piece of food and tends to hide now, remaining in the same place - hiding.
 
Recently I have noticed that my older angelfish, who once had nice fins, has been nipped right up his anal fin and now looks dreadful.  He then started to go almost cloudy around his eyes, but his eyes still remain clear.  I swear he hasn't eaten a flake or pellet in at least a couple of weeks.  He acts as if he is blind, except his eyes still look completely normal.  Flakes float right past him and he pays no attention to them.  He was once such a handsome and greedy fish, yet now he is neither and just swims around aimlessly.
 
I also have a couple of sick bleeding heart tetras.  I purchased them from my LFS in around September.  Basically, I got my first 6 bleeding hearts about a year ago.  They were gorgeous and have remained healthy to this day.  I then decided that I wanted a further 6, so purchased some more from my LFS.  They were small but all looked healthy and had good colours.  A couple of months later, I noticed that one of them developed fin rot despite their being no nipping within the tank at all.  I then found out that my friend who had bought some from the same batch also had some with fin rot.  I now have 2 with fin rot.  Her's did not respond to treatment and she had to humanely euthanise them.  I shall probably do the same
 
I'll admit that lately I have not paid so much attention to my tank, but I have still done PCWs as per usual and have checked every day to ensure all is well.  Today, I happened to look at my tank to see one of my gorgeous bolivian rams sitting on the bottom of the tank.  He was in full colour, and I just hoped for the best and went out of the room, albeit slightly confused.  Around 5 minutes later I came into the room to find him upside down on the bottom and he was just about breathing.  I was concerned and feared that he was beyond help.  Within around 2 minutes he was dead.  I was distraught as he is beautiful and they have been part of my tank for around 9 months - some of my favourite additions in there.
 
Now I piece it all together, I am very concerned.  There seems to be a lot of abnormal things happening - as mentioned above.  
 
Stocking is as follows:
 
200L Fluval Roma - AllPondSolutions 1400EF External (Up to 600L) and Fluval U4 Internal
 
11 x Bleeding Heart Tetras
4 x Three Lined Cories
1 x Bolivian Ram
1 x Angelfish
1 x Pearl Gourami
5 x Kuhli Loaches
3 x Bristlenose Plecos (One fully grown, one around 1.5 inches and one around 2 inches)
3 x Zebra Loaches
 
The Bleeding hearts keep to themselves and are quite friendly (Scaredy cats tbh! )
My concern is the Pearl Gourami.  He chases, but I have never seen him nip.  I am wondering if he is to blame for the nipping (Although I have NEVER seen him go anywhere near the angels)
 
I think there is some kind of "invisible" disease going around the tank and I am really worried.  That bolivian had no signs of illness right to the end.  He was in full colour.  I am baffled
 
I need to get my water tested, but last time I checked (About a month ago) all was 100% fine water paramaters wise
 
Please, any advice or input at all would be appreciated so much!
 

 

[mishmash]

A few things... firstly can you put a picture up of the tank. It often inspires people to think of things they otherwise might not.  Secondly, tell me how you clean your filter, including everything you do, and how often.  Do you have plants ? Do you use CO2 if so ? Do you have any kind of aeration ? How do you return your water from the filter ? What substrate do you have and how do you clean it and how often ? How often do you do a water change and how much ? Do you equalise the temperature to within a couple of degrees ?  Do you add dechlorinator ?  Just a few questions to be going on with  It would be good to get to the bottom of things.  Oh and when you put your hands/arms in the tank to do stuff, are your arms clean and free from hand cream and body lotion etc  ? It sounds daft but the number of people that dont think about that is rediculous.  

 

[LoachLover!]

A few things... firstly can you put a picture up of the tank. It often inspires people to think of things they otherwise might not.  Secondly, tell me how you clean your filter, including everything you do, and how often.  Do you have plants ? Do you use CO2 if so ? Do you have any kind of aeration ? How do you return your water from the filter ? What substrate do you have and how do you clean it and how often ? How often do you do a water change and how much ? Do you equalise the temperature to within a couple of degrees ?  Do you add dechlorinator ?  Just a few questions to be going on with

 It would be good to get to the bottom of things.  Oh and when you put your hands/arms in the tank to do stuff, are your arms clean and free from hand cream and body lotion etc  ? It sounds daft but the number of people that dont think about that is rediculous.  

 
I'll post a pic of it later when I get chance to take one 

 
I haven't cleaned my filters since around December, but when I do I use old tank water so as to not kill off the bacteria.  I do it by taking out the sponges, cleaning them in a bucket of old tank water and then I return them to the filter.
 
My tank is planted and I use liquid CO2 and a liquid fertiliser.
 
I do not have any additional aeration besides my filters, and they seem to aerate the water very well!
 
I use a sand substrate and I siphon any debris on top.  Every once in a while I agitate the sand.  I mostly clean it every week and around 30-50% dependent on how much time I have, but typically more toward 50% than anything else.
 
I make sure the temperature is about the same.  I have mixer taps that allow me to set the water to the temperature of the tank, which means it is the same more or less.
 
I use a dechlorinator - Seachem Prime
 
I don't put my hand in the water having used creams or lotions
 

 

[mark4785]

You ideally need to test your ammonia and nitrite levels of your water as fluctuations in these parameters can induce things like bacterial infections (i.e. fin rot). Even if you have 0 ppm of ammonia and nitrite, disturbing the substrate or even a filter that has become extremely dirty (presumably it is dirty if you don't often release the debris from the biological sponges; you can do this by simply dunking the filter sponges in a bucket of aquarium water) may cause trapped toxins, such as ammonia, nitrite and /or aeromonas bacterial organisms, to become released into the water column which will severely hinder the fishes' health when/if it comes into contact with them.
 
So firstly, please test your aquarium water for toxins.

 

[LoachLover!]

Sorry, I have tested my water paramaters.  Ammonia and nitrite are at 0 and nitrAte is around 5-10ppm, so all ok there
 
I am thoroughly confused as to what is going on

 

[mark4785]

Sorry, I have tested my water paramaters.  Ammonia and nitrite are at 0 and nitrAte is around 5-10ppm, so all ok there
 
I am thoroughly confused as to what is going on

After re-reading your thread I am 80% certain that the fact that you "agitate the sand every once in a while" is the sole cause of the the fin rot.
 
This is because sand always encloses anaerobic bacteria, ammonia and other nasties. These nasties build up over time; thus if you are disturbing the sand every couple of months or every month you are also disturbing/releasing toxins.
 
I uprooted some cyptocoryne plants in my aquarium to replace them. There roots had been submerged in sand for 5 months. The disturbance of uprooting the sand caused a haze of ammonia and bacteria to make contact with my bottom-dwelling Corydoras cat fish of which suddenly developed white-spot disease. 
 
It is an absolute no-brainer that lack of filter maintenance or disturbing vast amounts of sand or BOTH of these things are causing your fish to become ill.