View Full Version : Sudden Death: Danios

05-09-2009, 09:25 PM
When i checked the tank this morning all the fish were healthy and active and fed well, just had a look to find one danios dead. The tank is clean and cycled and water conditions are within the correct parameters what concerns me is behind the head there appears to be a large ammount of blood and it looks like it has bled internally (see attached images) i dont think he was attacked as there is no sign of external damage and its scales appear healthy. There is no sign of disease or stress with the other fish. This has happened completely out of the blue and im not sure why. Towards the back end of the fish on the underside as well i can see blood internally. Can anyone offer any explanation out of concern for the sadly deceaseds tankmates?

Little Embers
05-09-2009, 11:14 PM
Sorry to hear that! I really don't know what the reason good be and just taking a stab in the dark here. It looks like it could be some type of blood poisoning or caused by some toxin in the water (strange that it only affected one though). As you say, it could also be an internal problem. I know you mentioned your water parameters are within the correct range, Is there enough filtration/aeration in the tank and what was the temperature of the tank?

05-09-2009, 11:49 PM
he may have done a header off of the glass or tops. Those guys can really get up a head of steam.

Little Embers
05-10-2009, 12:03 AM
he may have done a header off of the glass or tops. Those guys can really get up a head of steam.

Yes! that is definitely a possibility....never thought of that!

05-10-2009, 02:49 PM
I am fairly sure its not a toxin as all the others are fine and it happened so suddenly with no behavioural changes. Tank temp is 19.2 C. Im inclined to go with the kamikaze fish explanation needless to say i will be keeping a close eye on the tank over the next couple of days and then decide wether to do a couple of weeks worth of super regular water changes if there is any sign of a toxin.

05-10-2009, 03:15 PM
Just a thought. You did test for ammonia, right? He looks a bit red around the gills as in ammonia poisoning. But it could be bruising from a header into the glass or other ornament.

Wild Turkey
05-10-2009, 03:18 PM
Yes, what are the tank parameters? Ammonia/nitrite/nitrate

05-10-2009, 04:35 PM
Ammonia 0.25
Nitrites 0
Nitrates 20


05-10-2009, 04:52 PM
Ammonia should be zero. I would do a substrate vacuum along with a 50% water change. Make sure there are no other dead fish in the tank. Retest for ammonia.

Wild Turkey
05-10-2009, 05:04 PM
Test it often so you can see if its on its way up for down. You have your most likely cause for the death though, looks like you had a mini cycle.
You dont need to do a waterchange at the moment though. If its on its way up however, well you get it.