Planted to Brackish

[rooster]

sick fox.JPG

Hi,
The hard facts. These numbers are as of today and pretty average for my tank and do not vary much, except the Nitrate which is sometimes about 40.
Gh = 180, Kh = 210
pH = 7.0, Nitrite = 0, Nitrate = 80 (little high but working on it)
salinity = 1.010
tank size is 240 litres, about 60 gallons with oxygen added.
I have had the tank for 3 years, initially as a planted tank. Now I have converted it to a brackish tank for the welfare of the 2 GSP's.
I do a 50 litre (15 gallon) weekly water change and only chemicals are a Biotopol water conditioner (for cholorine removal) and of course sea salt. I feed once daily, anything from mussels, blood worms, cockles, feeder shrimp, snails (flakes for the other fish).
Currently have 2 GSP's, 2 blue gouramis, 5 denison barbs, 6 harlequins, 7 Siamese flying foxes and everyone gets on fine.......until......

Spotted what looked like a bite in the one flying fox, both sides of him. Then he died and next one had it. Can't be bites, so figured they must be ulcers. And so this has moved from one fish to the next, setup a hospital tank but lost 6 flying foxes now. No other fish seem affected although 1 of the harlequins had fin rot and also died.
Doing lots of water changes but tank looks happy.

I'm wondering if there is something lurking in the substrate, since this was a planted tank for about 2.5 years. Loads of roots down there rotting. What I want to do is use my vacuum to suck up a bit of the substrate every water change and eventually be rid of it. But I'm worried that this substrate contributes to the tanks cycle and I might upset it all. I get no algae so its a good system. But what if the rotting roots are bad?
What is the best base for a brackish tank?
My 2 gsp's started the same size but one has by far outgrown the other and is about 5 inches now, the other about 2.5 inches.

Thanks for any advice!
cheers

[auto]

Personally id do partial water changes daily to.try and get that nitrate down thats quite high. Overstocking a problem? Whats the dimensions of the tank..

I wouldnt.have other fish in.with the gsps.

[scpion]

Your nitrate is a big problem. Its very high, not abit high.. I doubt u have anymore plants in there, even if there is, may not live long in brackish.. If i were u, i would remove the all the fishes temporary and clean out the substrate THOROUGHLY. If u have a good filtration in place, i wouldn't worry abt crashing the bio system. But clean it with the current water though. 15g wc/week is too low btw. We do 50%/weekly.

[scpion]

Btw if u started off with planted, u might be using base fert or those soil type with loads of nutrients.. If u are, best to change out totally. River sand/gravel will do for brackish. Some use crushed coral or argonite(spell check..) sand.

[rooster]

auto, I have had the same fish in there for about 1.5 years so think stocking is fine. they all seem to get on fine.
scpion, as you guessed the plants all died which I expect with the salt levels. don't really want to move fish as it would stress the gsp's. thats why i figure I can vacuum it all out...
thanks for the notes on substrate, it has to go and something simpler go in. definitely will up the water changes to work on the nitrates!
thanks for the replies!

[Pufferpunk]

Why can't it be a bite? Looks just like a pufferbite to me.

[spottedpee]

epic!

[rooster]

Pufferpunk, one of the fish that died had something on his eye. Some of the 'ulcers' were much bigger than bites and not uniform. Sometimes the loss of colour in the affected area was gradual, ruling out a bite. no other fish were affected. I doubt my puffers picked on just 1 species.
Its all just very weird....
I doing big regular water changes and have started to vacuum out old substrate, that nitrate level will come down.

[Pufferpunk]

Predatory fish will always pick on the weakest fish in the tank. Survival of the fittest.

[rooster]

pufferpunk I fail to see what value you are adding and think you time could be better spent watching the nature channel. survival of the fittest has nothing to do with why predatory fish eat other fish, it is a term used for the same species and is why the weaker will make way to the stronger.....
I just lost the 7th fish of the same species, no marks whatsoever. maybe the puffers simply beat him up without any marks, now that would be 'epic'...

[sevenyearnight]

Salt "burns" is my guess, freshwater fish absolutely cannot survive in that high salinity. Rehome/separate the freshwater fish from the GSP's.

[Pufferpunk]

pufferpunk I fail to see what value you are adding and think you time could be better spent watching the nature channel. survival of the fittest has nothing to do with why predatory fish eat other fish, it is a term used for the same species and is why the weaker will make way to the stronger.....
I just lost the 7th fish of the same species, no marks whatsoever. maybe the puffers simply beat him up without any marks, now that would be 'epic'...

Pecking order is natural for any species in a enclosed system. I just found 3 dead DPs in my larger DPs tank. NO marks on them whatsoever but I did see him chasing them around.

Please do not be rude. This is my site. If you do not appreciate my comments, you are welcome to find another pufferfish website to be rude on.

[rooster]

thanks sevenyearnight, I almost forgot about the affects of increasing the salt on the other fish. When I started the salt, i tried researching what the affects would be but could not find anything. Now from what you have said I think I have killed them with salt.....

pufferpunk, I have not been rude in the slightest. I wrote about a problem I am having with fish dying, fish I have had for 3 years and I want to try anything to save them. I was simply looking for advice, not sarcasm. On top of that, so often the finger is pointed at puffers...giving them a bad rep when it is not always the case.