Discoloration and "Bubble" on Black Ruby Barb
 

Dear Tropical Fish Keeping,

I realize you get a lot of these disease questions, so I'll try and be as brief as I can. I came home at about five, when I noticed that one of my four black ruby barbs had developed a white spot on it. This spot was not present yesterday. I have as of yet been unable to identify it; I looked through all five pages of the "Freshwater and Saltwater Diseases" topic, and did some googling.
I do not have pictures, but will post them tomorrow if the spot is still there. In the meantime I will try and describe it.

The spot appears to be under the fish's skin, and appears on both its left and right sides. On one side the spot is significantly larger, and almost has what appears to be a "bubble" under the skin. The spot is a white/faded blue color.
The fish otherwise seems fine. It is still active, and has a voracious appetite. However, and maybe I'm simply imagining this, all four fish almost seem to be acting more aggressive.

I should note that there has been a fungal infection in the tank, almost a year ago now.

I have a 29 gallon, Eclipse, aquarium.

As of yesterday:

Nitrate: 40 ppm

Nitrite: 0 ppm

Hardness: 25 (GH) ppm

Chlorine: 0 ppm

Alkalinity: 0 (KH) ppm

pH: 7

Ammonia: unknown

I use "Tetra Easy Strips; 6 - in - 1 Aquarium Test Strips" I plan on upgrading to a liquid test kit when I use the last of these.

I have a freshwater aquarium. No salt.

Almost five years. However, just recently all the fish have been replaced; and the tank re-aquascaped. Much of the under gravel substrate was stirred up.

I currently own four black ruby barb, each about an inch and a quarter long. I have had them since Saturday, and it is now Tuesday.

Not sure I understand the question. The fish were not placed under quarantine.

The tank water is roughly 74' Fahrenheit.

Yes. Lightly to moderately planted.

I am unsure. It is built into the aquarium's hood, has an H-sized charcoal cartridge, and a bio-wheel.
I also have a DIY bottle and gravel filter rated for ten gallons. I am giving my sister a ten gallon aquarium soon, and I hope to use this filter to jump start the cycling process.

No.

It receives some natural light from an adjacent window. This light is indirect. The lights are on roughly a twelve hour schedule.

I preformed my last water change one week ago. I preform a 20% to 33% water change weekly. I do vacuum the substrate.

I provide my fish "Wardley, Tropical Fish Flake Food". I feed them ten minutes after the lights come on, and between an hour to half an hour before lights off.

A white spot that appears to be under the skin.

No.

Thanks, Oyster Man

Can you post a picture if at all possible please?

No, but I did get this video:
29 Gallon Aquarium :: 2-22-12FishProblem.mp4 video by OetsyrMna - Photobucket


I'm growing more concerned for all my fish.
I came home today to find the black ruby barb, that was ill yesterday, isolating itself by the heater. It almost appeared to be twitching, and it reminded me of someone in the fetal position. On the bright side, the blister, which I was calling a bubble, seems to have resolved itself. The white spot is still there however.

Furthermore, all of the fish are acting very spastic. Their movements seem more random, and they will nervously dart here and there. At one point I was certain I saw one of them twitching back and forth. Every day, until today and yesterday, they've seemed very playful and active. Now they seem nervous and timid; and appear to be pale.

I've been thinking of recent changes I've made to the aquarium.:

My first hypothesis is that my nitrates may be causing the fish stress. My nitrates are at about 40 ppm, which is on the edge of the "safe zone" from what I've heard. I'm not quite sure what the effects of nitrates are, but I'm sure that high nitrates can cause stress, and maybe even poisoning.

I'm much more ashamed to admit my second hypothesis; I took a micro biology class two years ago, and it was plain stupid of me to do this. I was not thinking when I added the gravel to my DIY filter. I used gravel that was submerged in water. Seeing that it was in the dark, and very cold, I concluded that rinsing it in the sink would be enough sterilization. Obviously it isn't, and I feel I may have contaminated my aquarium with some foreign micro ecology.