Missing Fish....

[calzone]

Hello,

I have a 60L lightly planted tank, cycled, with two internal filters, one a fluval U2 the other an superfish aqua200. I had 3 platys, 4 zebra danios and 6 cory hastatus (plus snails, shrimp and it appears two baby platys (just under 1cm long).

Last week I noticed two of the danios had grey white patches on their backs. Another danio looked in distress and appeared to have lost half its tail. All the fish appeared to be "off colour". I researched this and to me it looked like an outbreak of columnaris. Since I'm in the UK I don't have access to antibiotics. so I went with aquarium salt, melafix and pimafix. The tailless danio didn't make it - by the time I found the body and fought off the snails he had no fins at all.

Now 6 days later, the other danios patches appear to have gone. Fish behaviour is more normal. However, however hard I try I cannot find more than 3 (or maybe 4) of the corys. I have also had one or two short lived ammonia blips up to 0.25-0.5ppm in the last week which I have traced (I think) to very low flow in the U2 filter due to sludge build up. However, it is possible I suppose that this could be the result of a decaying fish body? Is it possible that a tiny cory (1.5cm?) body could be completely consumed by snails etc overnight leaving no trace? They could be hiding (very rarely see more than a few shrimp for example) but they always used to shoal very nicely so i suspect the ammonia blips / columnaris have done for them...

I have since bought an external canister filter (all pond solutions 1000ex+ with 9w UV) which I though might be massively too big but is actually fine (loaded with bio media so probably making half its rated 1000lph), transferred the media from the U2 into it and all readings 0ppm for nh2/no2 and 30ppm for nitrate (tap water at least 20ppm).

Melafix/pimafix instructions say to continue for one week. Does anyone have experience with these - should I stop tomorrow or would it be better to carry on given the possibility that the attack was columnaris? Also, while its nice to have baby platys, at this rate I am going to be very overstocked..... Do fish shops take these back? (I know, I know - just ask them!!).

Any advice appreciated.

 

[scaeriefaerie666]

I've never used Pimafix before, though i have used melafix and do regularly when i have problems. I would say carry on with the melafix as it's not an invasive chemical and it's quite natural. I don't know about pimafix so i shan't give you bad advice.

I would say that it is very possible that the snails may have eaten any dead fish, and depending on their size it makes a huge difference as to how quickly that could happen. Its horrible losing fish (and i mean actually losing them, not them dying but going missing). I had an aquatic frog do a houdini. It was horrible.

Do a really good search and stir up the gravel and suchlike to make sure that they aren't just hiding but i'd say you're pretty much on top of it, from what you've said.
xxx

 

[calzone]

Thanks. I did occur to me that losing only one fish to a bacterial infection with ammonia spikes was unlikely, and by all accounts corys are not that robust. Unlike platys, which so far appear to be made from steel, touch wood. Given how closely they shoaled before the problems, I'm struggling to believe they're all still there somewhere. And there are many snails in there so they could make short work of a small fish. I must be overfeeding to get this many snails.... that and my assassin snails are lazy.