Are My Black Neons Sick?

[Flying-Minnow]

Ok so I've had my Black neons for a few days now. I've got five of them, and got the heater at 24celceus. I was told this was hot enough for them and for other fish I want to put in.

I had my tank running for a whole week to let the chemical scycle kick start (to get rid of the chlorine and yuck in tap water) then started a fish in cycle. And it's only been a few days (I got them Monday 7th) I've had them. As far as I know every thing is how it's meant to be (electrical equipment working, heater working, feed once a day, etc)
as I said im doing a fish in cycle.

Two of the fish have what look like a large bump that is silvery white in colour on the right side of their body, there is no other marks on them. The other three seem healthy, acting normally. Hanging in the water flicking fins every now and then before swimming around a little, and then dissapearing behind the plants.
The other two are doing that, but have started to act agressively towards each other (just the two), and not towards the ones who are not affected.
It just appeared today, there eyes are not smoked over. They eat really well, and want more food after. But I don't want to over feed them as they wont eat it all.
They come up to the top of the tank to be fed (in just a few days they do this), I was advised for a week to feed them a little while the amonia and nitrate and nitrose (what ever the other one is) lowers.
I know the black neons are better in 6+ shoals, but I was advised not to put too many in at first or it would over load the system while the good bacteria is building up or I would loose them all.
I don't want to loose any, and want to know what I may be possibly dealing with so I can nock it on it's head before it gets any worse.

It doesnt look like white spot or ick as they both are tiny spots, this is a large bump, like a huge zit. and it's silvery white in colour.

They are in a 30L biorb, I was told by pet shop that they would be ok in that tank, but a few people have told me they are too big for the tank when the are fully grown.
I'm a little confused.... help

 

[waterdrop]

Hi FM and Welcome to our freshwater beginners section!

Black neons are a very pretty fish! A fish-in cycle can be a life and death situation for tropical fish and it's very easy for beginners to confuse various details or not be told all they need to know to pull one off.

You have not reported the numerical results of your water tests, which leads me to ask whether you have a test kit for your water chemistry? For me, this would almost be the first thing I got even before a tank! The test kit needs to be a liquid-reagent based type and most of us like and use the API Freshwater Master Test Kit.

It may be that you're already using a kit, but I'm concerned from your descriptions that you may either not be using one at all, may be relying on the pet shop or may be using paper strips to test. Your fish may be in urgent need of a large (75% or more) water change. This needs to be done with proper technique. If possible a gravel-cleaning siphon should be used to clean the gravel as the water comes out, but regardless, even without that the large water change may be needed right away. The return water needs to be conditioned (to remove chlorine or chloramines) and roughly temperature matched (your hand is good enough.) If you don't have your tests yet then a 50% change should be repeated daily until (soon, hopefully) you can test and post the results for the members.

When fish respire (move water through their gills) they give off ammonia from the gills. Fish waste, excess fish food and live plant debris all break down to create still more ammonia. Ammonia, even in tiny amounts, causes permanent gill damage. In nature, thousands of gallons of fresh water carry the ammonia away from the gills.

In a working "biofilter" (what we are trying to create with the "chemical cycles" you referred to so that we won't expose fish to poisons) we are trying to grow two specific species of autotrophic bacteria. The first of these, the ammonia oxidizing bacteria (we'll call them A-Bacs) can convert the deadly ammonia(NH3) into nitrite(NO2).

Nitrite(NO2), even in tiny amounts, suffocates fish by attaching to blood where oxygen would normally, causing permanent nerve damage or death. The second species of autotrophic bacteria we grow, the nitrite oxidizing bacteria (call them the N-Bacs) can convert nitrite(NO2) into nitrate(NO3) which happens to be far less deadly to fish and we can remove it with water changes. So the biofilter and our water changes are the life-giving support that keep our fish alive in their artificial environment! They depend on it daily! The biofilter is like magic, but when our tank is new it hasn't got one!

The bacteria take often about 70 days to build up to the levels we need and until then we need to either change the water ourselves (to be a manual biofilter) or if we are running what's called a fishless cycle we need to periodically dose the tank with a tiny squirt of ammonia. In either case we need to run our water tests once or twice a day until the filter is built.

Good luck with your time here in the forum and I hope it will turn out that the black neons are not sick! Sorry for all the words (probably you already knew all that!)

~~waterdrop~~