Trying To Identify Disease In Community Tank

[Bazouteast]

After a few years lay-off I set up a community tank 6 months ago with Dwarf & Honey Gouramies, Chequer Barbs, Angels and Mountain Minnows. About 15 juvenile fish. The symptoms are a wasting of the fin edges consistent with fin-rot, also ulceration at the base of the tail causing the tail to slowly drop-off. Also lesions on the body and head. It’s been going on for 2 months with the Angels, Barbs and Dwarf Gouramies hard hit but the Honeys and Mountain Minnows seemingly immune.  I placed the Dwarfs and one Angel in an isolation tank with Methylene Blue for nearly three weeks. The Angel lost its appetite and wasted away, the male Dwarf is heading in the same way, while the female Dwarf developed what I could only recognise as Hole-in-the-Head disease - I haven’t seen that for decades.  It became so ugly I terminated her.
 
The only difference with my tank this time around is plastic plants – realistic, cheap, colourful and washed well before use.  I’m wondering what the cause might be, if it is one infection or many, and why it hit the Dwarfs but not the Honeys, the Barbs but not the Minnows.  The fish came from several suppliers. Wherever possible I select each fish individually and none had symptoms when purchased. The symptoms developed 3-4 weeks after purchase.
 
TANK DATA
150L tank running a big Fluval 303 filter with a surface spray bar.  I’m using London tap water, with 30% change pw. Data has been static for months. NO3 <10mg/l; NO2 0mg/l; General Hardness >14˚/ <21˚; KH hardness 10˚; pH 7.6; NH3 0ppm. Water temp is approx. 24C. Staple food is dried flake supplemented with frozen bloodworm, artemia or mosquito larvae once or twice a week.
 
Any suggestions appreciated.

 

[Far_King]

From your description and indeed from most descriptions regarding symptoms in fish, it's very hard to diagnose exactly what the disease is and especially the cause (usually newly introduced fish).  Even identifying disease in your own fish can be a very difficult process.
 
I would suggest perhaps having a look at this link to see if you can narrow it down : http/www.fishnet.org/sick-fish-chart.htm
 
And then here for a guide to potential suitable medication http/www.liveaquaria.com/PIC/article.cfm?aid=202

 

[Akasha72]

I think the clue here is the water. Angels and gourami's are soft water fish. Keeping them in an enviroment they are not designed for would have caused extreem stress and from what you are describing of the angel it succumbed to Hexamita. Hole in the head is also linked to Hexamita as both are caused by bacterial infections.
 
Dwarf gourami's are also in the grip of dwarf gourami disease at the moment. There is no cure of this disease yet and so they are best avoided unless you are buying them from a specialist breeder who is aware of where his stock is coming from and know's they are disease free. This disease only affects the dwarf species and this might explain why the honey gourami hasn't succumbed. 
 
When it comes to re-stocking your tank it would be best to avoid adding soft water species to it. Do your research and decide on fish that can live with the water you have. If you want to keep soft water fish then you'll need to look to switching to RO water or find ways to soften your water

 

[Bazouteast]

Thanks FK - the chart is very helpful. And Akasha for the helpful advice. The chart suggests I'm dealing with at least two condition. But as I mentioned, the Dwarf but not the Honey Gouramies were affected which suggests part of the problem could a third condition - Dwarf Gourami Disease which I have never heard of. I'll definitely research that one.  The dealer said the Angels were bred in London tap but I don't know if being born in it means its OK to spend the rest of their lives in it.
 
Thanks for your help.

 

[Far_King]

Dwarf gourami disease as Akasha says is pretty common sadly. 
 
I lost four to it within a few weeks of buying the fish.  I'd not get dwarf gourami again personally.

 

[Akasha72]

in answer to the angel. It's a common misconception that fish have 'evolved' to live in different water to what they were 'designed' for. I read many times that tank bred soft water fish can live in hard water and I don't believe this to be true. I do believe that they can survive in it but surviving and thriving are two different things. In the wild angelfish live in water with a pH as low as 4.5. In our aquariums we can have a pH up into the 8's - this is the opposite of what the angels are living in in the wild.
Over the years many soft water fish have been tank bred in pH ranges far higher than they would be in the wild but that does not mean that they can thrive in it. Many fish keepers will tell you that they are 'fine' and that they can not see anything wrong but that is because the damage is being done in area's we can't see - their kidney's being the main organ affected by being kept in hard water. Whilst they have evolved slightly and can thrive in harder water than they do in the wild they still need to be in soft water conditions with a low pH, gH and kH
 
Byron explains this very well, perhaps he'll be along to explain it in far more detail