Fish rubbing on the side of the tank?

[Denbros]

Help!!! My fish have been running against the aquarium side. They don't rub against any decorations or any gravel. They only spend their time rubbing against the wall of my fish tank. I had this aquarium running for more than 5 weeks now.

Fish: Fancy tailed goldfish

TANK: 36 gallon bowfront

Test kit: API liquid test expires in 2020

Water conditioner: Fluval Water Conditioner 500 ml 16.9 fl Oz

Ammonia: 0.00 ppm

Nitrite: 0.0ppm

Nitrate: 0 for some reason

PH: 6.6-70

Chlorine: probably 0

Alkalinity: I don't even have the test kit lol

Algae growth: Brown UGLY STUFF

Temperature: 25 degrees Celsius

PLS HELP ME

 

[Delapool]

Help!!! My fish have been running against the aquarium side. They don't rub against any decorations or any gravel. They only spend their time rubbing against the wall of my fish tank. I had this aquarium running for more than 5 weeks now.



Fish: Fancy tailed goldfish



TANK: 36 gallon bowfront



Test kit: API liquid test expires in 2020



Water conditioner: Fluval Water Conditioner 500 ml 16.9 fl Oz



Ammonia: 0.00 ppm



Nitrite: 0.0ppm



Nitrate: 0 for some reason



PH: 6.6-70



Chlorine: probably 0



Alkalinity: I don't even have the test kit lol



Algae growth: Brown UGLY STUFF



Temperature: 25 degrees Celsius



PLS HELP ME

I think these would the questions I'd look at. Along the glass is pretty odd, I don't think I've ever heard of them just doing that.

1) would be to check if any red marks, excess slime, ruffled scales or flicking on ornaments around the gills that might indicate parasites.

2) would be to test tap water for all test kits and see what the base line is. Hopefully you will get a slight colour change to tank water to show the tests are working as 0 readings across the board for ammonia, nitrite and nitrate are quite rare. To be honest, if still getting 0 values I'd take a sample of water into a fish shop to get it tested for peace of mind.

3) would be to see if doing it all the time or worse at any time. Also if any particular area and if after a water change.

What is the substrate? Is there any sand? This could indicate the algae is diatoms which should die out. If just ordinary gravel, then I'd reduce lighting to 6 hours.

4) if ph is 6.6 and lower than tap water ph I would add a small bag of crushed coral (say a handful) which will buffer your water.