I have a question similar to corielover's post about a mysterious white spot appearing on a young Ancistrus. First the parameters of the tank:
1. Water parameters
a) Temperature range - over the last three days is have varied from 76.4-76.9
b) pH. 6.64-7.14 (the changes are due to CO2 injection). pH is highest at 8:50am before the CO2 turns on and lowest at 8pm when it turns off.
c) GH. 180
d) KH 60
e)Ammonia: 0 Nitrate: 5 Nitrite: 0
f) Water change frequency: currently 1 gallon per day but spread out in small amounts throughout the day, with small changes occurring automatically every 2 hrs. TDS reading this morning was 350. New water is RO water reconstituted with Equilibrium, discus trace (LFS was out of Freshwater trace), acid and alkaline buffers (1:2 ratio). I started monitoring ORP three days ago so these readings may not be very accurate yet but it fluctuates between 233-246 (no daily pattern following pH yet) except when the CO2 turns on, then it decreases to 80-90 and over the course of an hour comes back up. There is also a small decrease during feeding, for example it dropped from 236 to 230 during regular feeding and down to 218 when I added the cucumber. But, within 20-30min it comes back up. Dissolved O2 reads higher than 8, but less than 12 (my test kit is not more precise unfortunately
)2. Tank set up
a) Size: Currently 20G, but inhabitants will be moving to 55G in a couple weeks with upgraded filtration once the tank is ready.
b) Substrate: Seachem Fluorite black sand
c) Filtration: Eheim Pro 3e with 5W UV and TMC V2 #600 fluidized sand filter
d) Furnishings: variety of plants stem and floating, wood, some rocks to make caves and two round ceramic caves. Seachem line of plant fertilizers are dosed automatically as is an IAL tea that is made in weekly batches from dried leaves. One air curtain on 24/7.
e) Other tank mates: neon tetras, 2 Synodontis hybrid 9, Stiphodon sp. (gold spot goby), glass bloodfin tetras, peacock gobies, habrosus cories and pygmy cories, variety of shrimp.
f) How long has it been set-up? 13 months
g) When was the last new fish added? June 14 (6 pygmy cories)
h) Foods used and frequency? Hikari micro pellets (daily), Hikari sinking wafers (daily), Hikari algae pellets (daily), Repashy soilent green (weekly), blanched cucumber or zucchini (twice a week), Hikari frozen blood worms (daily), Cobalt brine shrimp pellets (once a week), Hikari carnivore pellets (once 2-3 days). I tried Repashy community, it received a mild reception so I haven't used it more.
3. Symptoms / Problem description: This morning I noticed a white-ish spot on the left side of the Ancistrus's face behind his (?) cheek odontodes. I looked at pictures of him from earlier in the week and while there is a lighter coloured spot in the same area, it looked just like part of his natural pattern and I didn't think any more about it. Today, it is noticeably white. It is not "cottony" as a fungus would be, it is completely flat, it seems like the colour is simply gone. He eats and acts normally, although yesterday he was more possessive of the cucumber than he normally is.
Any suggestions as to what this might be would be greatly appreciated
