This site is supported by the advertisements on it, please disable your AdBlocker so we can continue to provide you with the quality content you expect.
  1. We are after as many aquarium plant images that we can get, doing so will assist us in completing the aquarium plant database.

    https://barrreport.com/threads/aquatic-plant-images-wanted.14374/
    Dismiss Notice

Suicide Raspboras

Discussion in 'Fish for Planted Tanks' started by brownleaf, Apr 30, 2020.

  1. brownleaf

    brownleaf Subscriber

    Joined:
    Sep 27, 2016
    Messages:
    8
    Likes Received:
    4
    Local Time:
    6:24 PM
    My harlequin rasboras seem prone to suicide by jumping out of the tank. I have a hypothesis ... but also want to check with the community here for any other ideas.

    This is my first serious high tech planted tank, and my first rimless and cover-less tank. Its a 18"x18"x36" (45 gallons or so) rimless tank, CO2 injection by conventional diffuser, filtering with Oase Biomaster 350 using a lily pipe outflow and a skimmer inflow. Substrate is UNS Controsoil aquasoil capped with Seachem Fluorite. Lighting is two Kessil A350WE running lower than maximum brightness with a fairly short photoperiod Water parameters are
    kH 4-5 degrees
    GH ~12 degrees
    pH about 6.8 before CO2 comes on, drops to about 5.9 with CO2 Drop checker eventually gets to yellowish-green by the end of the day with pH at 5.9
    -- tap water here has pH 7.4-7.6; in this tank with the aquasoil substrate it lowers to about 6.8

    The tank took about a month to cycle fully before I added any livestock, and I've gotten through the first two months of the tanks life with only minor algae issues. So far the plant growth is pretty acceptable by my standards.

    the fauna includes a (dwindling) school of Rasbora Het, a (growing) school of white cloud minnows, a handful of otos and Amano shrimp and a few snails. The white clouds and otos went in first, then the harlequins and amano shrimp a couple weeks later. The white clouds spawned and the fry are growing up in a breeder net hanging in the tank.

    Only the harlequin rasboras are jumping out of the tank- I've lost 3 over the past few weeks since I added them. None of the minnows have leapt to their deaths.

    The pattern I notice is that the rasboras jump out some time in the early morning. In both cases of jumping (one fish the first time, two fish the second time), there were no jumpers at or after midnight but at 8am there was a dead fish or two on the floor. The morning after the double suicide, I also found one rasbora limply floating and thought it was dead but it swam away when I disturbed it and later in the day seemed perfectly normal.

    My current hypothesis is that the CO2 running before the lights turn on got too high without enough dissolved oxygen. I had the CO2 starting up 2.5hrs before the lights came on. The pH doesn't go below 5.9 in the morning but the tank is heavily planted. Even with lots of surface agitation and the skimmer keeping the surface free of scum, I wonder if the plant respiration is creating a low oxygen environment that the fish are trying to escape.

    The otos and white clouds and shrimp don't seem to have any problem and the pH drop is less than what many on this forum report is possible while maintaining healthy fish. I don't see the rest of the fish gasping at the surface of the water.

    For now I've shortened the time the CO2 runs before the lights come on to just 1 hour and I'll see if that stops the suicides. But in the interest of saving more fish before I figure it out, I'm happy for any other recommendations.

    Are harlequin rasboras known to be jumpers? I hesitated to add a cover to the beautiful rimless tank which also would make the CO2 management more challenging. But neither do I want to be killing fish.
     
    #1 brownleaf, Apr 30, 2020
    Last edited: May 5, 2020
    Mike Go likes this.
  2. brownleaf

    brownleaf Subscriber

    Joined:
    Sep 27, 2016
    Messages:
    8
    Likes Received:
    4
    Local Time:
    6:24 PM
    Well, my hypothesis of too-early CO2 with too-low oxygen as the cause of jumping may be proven false. Two days after I adjusted the start time of CO2 to 1.5hrs before lights, I got another jumper dried up on the floor. :( I've adjusted the lights to come on earlier at low intensity but now I'm less hopeful this will quell my harlequins' suicidal tendencies.
     
  3. brownleaf

    brownleaf Subscriber

    Joined:
    Sep 27, 2016
    Messages:
    8
    Likes Received:
    4
    Local Time:
    6:24 PM
    By now I'm sure my original hypothesis was not correct. I have my CO2 coming on less than an hour before the lights, and the lily pipe and surface skimmer keep good surface agitation and scum-free surface. In the two weeks since my last update I've had two more suicides. Now I'm left with only 3 of the 9 harlequins I started with, all 6 lost to jumping. And all this time not a single White Cloud has wanted to escape.

    I guess at this point my only choices are to cover the tank or to not try to keep harlequins. Its too bad because they are one of my favorites. Even Tom's famous tank that adorns these forums is populated with these charming little fish. I still feel like there's something wrong in my tank; if these fish were such consistent jumpers by nature they woudl't be so popular in planted tanks which often have open tops.
     
  4. xrayguy

    xrayguy New Member

    Joined:
    May 13, 2020
    Messages:
    1
    Likes Received:
    0
    Local Time:
    11:24 AM
    Have you tried lowering your water level a bit? It might take away from the look of the tank a bit, but it beats a lid!
    Amanos can also crawl out of your tank. I haven't happen to me, but have read about it.

    I've had several eyespot rasboras jump out of my 75g tank, and it only had a 1" opening in the lid.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice