Black patches/ spots on fish?

[Miggy1234]

Hi all

Hoping to get some professional advice on what this could be? Recently only one of my fish have displayed this.

1~What type of fish is afflicted? In addition, please describe what is wrong with the fish to the best of your ability (i.e. cotton like growth, bloated, etc.).

Small fantail fish. Fish has displayed some small black dots on the side of its body as well as forehead. This fish was previously completely orange and acting normally. The fish is now acting slightly lethargic, heavy breathing and keeping away from the rest of the fish. Dorsal fin still high and comes to surface to eat. Iv had this fish for about a year and only in the past few days have noticed this. All other fish are acting normal.

2~What are your tank parameters (ammonia, nitrites, nitrates, temp, pH)? Please give exact values.

Tested this morning.
Ammonia 0
Nitrite 0
Nitrate 30ppm
Ph 7
Temp (not tested as I don’t use a heater for goldfish)

3~ How large is the tank? How long has the tank been set up?

200L and setup for up to 2 years now

4~What type of filtration are you using? Please give the name and number (i.e. Fluval 304) and amount of gph if known.

2 HOB filters and one small canister filter

5~How many fish are in the tank? What kinds of fish are they and what are their current sizes?

5 in total and all around 3-4cm

6~When is the last time you did a water change and vacuum the gravel? How often do you do this? How much water do you remove at a time?

A few days right before Christmas, I did a water change of probably 40%. I also cleaned the Anubias I had in the tank (scrub the black algae in seperate container or tank water). Iv never cleaned the plants before. Also rinsed the HOB filter as per normal.

Normally I only do a 20% water change with filter rinse at least once a month as tank i don’t feed my fish that often


7~How long have you had the fish? If the fish is new, how did you acclimate it/them?

Up to 2 years.

8~Have you added anything new to the tank--decor, new dechlorinator, new substrate, etc.?

No

9~What kind of food have you been feeding your fish, have you changed their diet recently?

Hikari small pellets. Same diet as usual. I did go away the past few days so could not feed the fish for a few days but have resumed upon return.