Otocinclus.. sys., comp., beh.    3/22/11
Hello,
My name is Jessica, thank you for your help in advance. I have been keeping Goldfish ever since I got my first ten gallon aquarium at the age of nine.
For the past two years, I have had a 29 gallon freshwater planted tank, which is also home to one brand new, week old, two inch Fantail Goldfish and two Otocinclus.
<Mmm... not really compatible fishes... like very different water quality mixes>
The tank parameters are as follows, pH 6.4,
<Low for Goldfish>
Nitrites 0, Nitrates 20ppm or less,
<I would not let the NO3 concentration get any higher than this maximum>
Ammonia 0, and temp 70-72F. I do a weekly 25-50% water change and vacuum the gravel at the same time while tending the plants. It is well water so I don't need to add a dechlorinator. I bought the two Otocinclus about two months ago and they have done an amazing job cleaning up the algae in the tank. At the time the aquarium was home to an eight inch, five year old Bubble Eye Goldfish who has since passed on. His one eye bubble got so big that he kept catching it in his mouth. It became irritated and in the 24 hours that I was not there it managed to become infected and swollen. I placed him in the hospital tank and gave him antibiotics but sadly his eye popped and he died two days later. Since then I have been substituting the Otocinclus's algae diet with some zucchini and Spirulina wafers and have left the back and sides of the tank alone for them to clean. When I first got them they both had Ich and one of them had almost its entire caudal fin missing. Unfortunately, I read that this was rather commonplace during the shipping process.
<This is so>
Anyway, its fin has regrown and they both seem to be doing fine. What concerns me is that their dorsal fins always seems to be held tight against their bodies, they have been this way since I got them, is this just normal behavior for them?
<Mmm, yes. A general statement re freshwater fishes is that their fins are "down" for most of the time, vs. marine fishes, whose fins are "up" most of the time>
They seem happy otherwise zooming around the tank and they really love their zucchini, although the new goldfish is fighting them for it. Also, I was thinking of raising the pH just a little bit, up to 6.8, and to this end was thinking of boiling some shells, cracking them, and placing them in a glass bottle in the tank.
<Worth trying>
That way the fish could not get cut on them and they would be easy to take out if the pH got too high. Do you think this is a good idea or would you recommend to just leave the pH alone as is?
<I might instead add a bit of sodium bicarbonate (baking soda) to a given batch of make-up water (in storage and tested ahead of use) to get a proportion of how much you'd be adding to raise the pH on a regular basis... but the shells are again a good/safe source. Bob Fenner>

Cory/Oto behavior change  5/19/10
Hi crew:
<Ave,>
Thanks as always for all that you do.
<Kind of you to say so.>
My question concerns a change in behavior by some of the fish in my tank. Tank specs as follows:
Tank: 10 gallon standard
Filtration: Aqueon 10 HOB with pre-filter sponge (x2) each rated for 100gph
Temp: 76F
pH: 7.2
NH3: 0ppm
NO2: 0ppm
NO3: ~10ppm
Above tested via API Freshwater Test Kit
Total Alkalinity: 180ppm (tested via strip... not really sure what this number represents)
<Middling hardness, fine for most purposes.>
Total Hardness: 120ppm (tested via strip... not really sure what this number represents)
<Similar. Do read:
http://www.wetwebmedia.com/fwsubwebindex/fwh2oquality.htm
>
20% water change weekly
Flora (moderately planted):
Cryptocoryne wendtii x2
Cryptocoryne parva x2
Anubias barteri v. 'Nana'
Microsorium pteropus
Ceratopteris thalictroides - rooted
Eleocharis acicularis
Remnants of Java moss - mostly removed as it was constantly infested with thread algae
<Yes, never had much luck with this plant myself. Always seems to do well where I don't want it, but badly everywhere else.>
Hitchhiker duckweed
<The world's best ammonia remover! A blessing of sorts, but a nuisance I know.>
Fauna:
Corydoras pygmaeus x6
Boraras maculatus x15
Otocinclus affinis x3
Assassin Snails (started with 2 adults, now numerous juveniles)
Hitchhiker pond snails
<Sounds grand! It's a real joy to read about a sensibly stocked 10 gallon tank.>
Tank was set up and planted in October, stocked in January.
<OK.>
I've observed a change in behavior in my Corys and Otos over the last few weeks. In the past, the Otos would spend time on the front and side glass of the tank during all hours of the day/night. Lately, they stay in the small space between the HOB filter and the back glass of the tank.
<Possibly more food there?>
They will venture down to the substrate at night to eat algae wafers (Hikari brand), but ignore the blanched zucchini and carrots I place in the tank which they used to eat with gusto.
<Interesting.>
The Corys, while always skittish, used to venture around the tank in a shoal, especially when I fed the Rasboras. After not seeing any of them for weeks, and assuming they had perished somehow, I found them hiding in a tiny crevice, all on top of each other, between the driftwood and the substrate, when I shined a flashlight into the tank to try to find them. They also now seem to venture out only at night for the sinking wafers (Hikari brand) I place in the tank at lights out. I know that Corys are nocturnal in the wild, but this is a recent development, hence my concern.
<Indeed.>
I'm not sure what caused the change in behavior as my feeding and maintenance regimens have remained the same. Water quality has also remained constant.
<That would be my first though, as well as variation in pH and problems with oxygenation. Since both Otocinclus and Corydoras prefer cooler rather than warmer conditions, check the temperature. 25 C/77 F is the absolute tops for both species.>
My first thought is an aggression issue with the Rasboras, but I have never observed any aggression.
<Unlikely.>
I had also thought that I might need to add Corys to the tank to see if increasing the size of the shoal would bring them out into the open more often, but I believe my tank to be fully stocked as is.
<Oh, I'd chance it. With all the plants I think you'd be fine. I'd keep at least 5 Otocinclus, and maybe double the number of Corydoras pygmaeus. All these fish are so small that their impact on water quality would be fairly trivial.>
Do you have any thoughts on what would cause this change in behavior and if there is something else I should be doing?
<My guess would be something is scaring them -- too much overhead light, noise/vibration outside the aquarium, banging doors or some such. Direct sunlight can also be a thing. I have a 15 gallon tank that gets direct sunlight for a couple of months of the year, and the way the fish behave becomes noticeably different during those times. The Corydoras paleatus in particular cluster in one particular shady spot under the Anubias mother plant.>
Thanks in advance.
Ben
<Cheers, Neale.>

Otos coloration: Sick or normal? I got four new Otos on Monday. Stupidly, I put them in my tank without first a quarantine (this won't happen again, trust me). I may just be paranoid but I am wondering about their coloration. It looks splotchy to me and I was wondering if this is normal or if it might be something I need to take care of.  < Hard to say what the problem is. It is normal for fish to have a fright pattern when being introduced into a new tank. As they begin to feel more comfortable than they start looking more normal. Many times these algae eaters are starved at the wholesalers and at the local store. I would place an algae wafer in the tank at night to make sure they are getting something to eat. If the splotchy pattern continues with all the fish or gets worse then I might start thinking there is a problem. -Chuck>  I am attaching two pictures. If you need any other details, please ask. Thank you for your time.  David

Once playful Otos are now lethargic   7/28/06 Hello there, <Hi from... HI!> For the past 5 months, I have owned a 46 gallon, unplanted tank, containing 10 rummy nosed tetras, 10 black phantom tetras, 4 peppered Corys, and 3 Otos. <Better with live plants...> The Otos were originally quite playful, moved around the tank, stayed within view, interacted with other fish and ate any algae that appeared.  However, for about the past month, the Otos have been in hiding. <Something in the way of water quality changed> Now I hardly ever see them, and algae is building up on the glass and plastic plants.   They don't appear to be sick, and none have died.  All the other fish appear to be normal.  My water temperature has increased to about 82 degrees due to the warmer summer weather, but besides that, I can't think of anything that I've changed. I do 20% water changes once every week or two, and nitrate level is 12.5 mg/L or lower (my test kit measures only measures 1, 0, 12.5, and 25 mg/L).  I don't add any "Oto specific" food to the tank.  Might I simply have more algae than they can handle, allowing them to become more "lazy"?  Do you have any thoughts on the matter? <Yes... I definitely would add some live plant material here... Will address many possible ills, shortfalls that could be at play here... Dissolved oxygen, food, shelter...> Thanks in advance for your help. Bonnie <Welcome. Please read here: http://wetwebmedia.com/FWSubWebIndex/otocinclusart.htm and the linked files above. Bob Fenner>