Tiny pimple on outer gill

[Kawaii]

Hi,

I'm a new arowana fan. My 6inch pearl jardini has been in my 2.8feet x 1.6feet tank for one and half week. The tank has been cycled for one week before I put my arowana in it, and I placed 2 small catfishes (Cory Cats) while cycling the tank. (Actually I had 2 mollies and 2 guppies when cycling the tank but the arowana ate them all three days after I set the arowana loose in the tank).

I have two types of filter system, undergravel and overhead trickle filter, and there's also an air pump. I just changed 20% of the water a few days ago.

Today I noticed there's a small white "pimple" or spot which seems to be inside the soft part of the gill cover. Other than that, the jardini is swimming around and is still eating. Is this spot dangerous or some sort of ich?

I feed it dried shrimp and frozen blood worms, twice a day. In the past 2-3 days, it's not as enthusiastic about eating the shrimps, and seems to be having trouble "chewing" and would spat out some parts of the shrimps. In the beginning, it would just eat aggressively and swallow the shrimps whole. But now I have to chose small shrimps or resort breaking the shrimps into small pieces and take off the heads, but it still seems to be having trouble eating some of the shrimps.

One of the Cory Cats just died today. For the past 2 days it was lying listless, breathing heavily and didn't eat or move so I knew it was sick. The other Cory Cat start to exhibit the same lethargic symptom today. I don't know whether the Cory Cats have diseases in the beginning as I bought them from a different LFS than the jardini, or simply that Cory Cats and Arowanas just don't mix.

In any case, I'm afraid if there's something wrong with the water because the Cory Cats are dying/dead, but the arowana is still ok, except for the white pimple.

Do you have any suggestion? Would appreciate your feedback.

Thanks.

[Isna]

hi kawaii,
WELCOME!
hehe...sounds like problem indeed.
yeah bro..check your water.
any parameters?

i'll definitely race off n do a water change, say40-50%..
add dechlorinator, let it mix for 5 mins or more, make sure the temp is the same, THEN siphon or tip it into the tank.
add aquarium salt or rock salt( not the usual table salt if possible), at 1 generous table spoon per 10L of water.

About the lesion, just wait n see i guess....let's stabilise the water first...so to speak.
Have u done a complete physical exam? check it's breathing? skin? fins? etc?? u don't want to miss something.......try 'approaching a case' to guide u through the examination.
all the best!

[Kawaii]

Hi Isna, thanks for the welcome.

I've tested the water...ammonia is 0 and ph is 7.6. Do I need to lower the ph (and if so, how) and test for nitrites (or is it nitrates)? What's the difference between tests for ammonia and nitrates?

My aro is still swimming about, and today the appetite is good although it spat out the shells of a few small krills. I suspect it doesn't like to eat the dried prawns if they are too small and not meaty.

Anyway, the white spot is still there. I haven't changed the water since the water parameters is ok and I just changed the water on sunday.

Oh, btw, my other Cory Cat just died this morning. So now my aro is all alone. Still not sure why the Cory Cats died.

Ciao for now.

[Kawaii]

BTW, Isna, just to add to my last message, you told me to add 1 tablespoon of salt for every 10L. That means I have to put about 50 tablespoons???? Isn't that too much and won't freshwater turn to saltwater afterwards???