Sick Zebra Danio - Going Crazy

[TraceyB]

My dad has a 30L cold water Biorb that houses 6 danios.

The tank is cycled and the fish have been fine up to now.

When I visited this morning (mother's day UK) I noticed one of the danios lying at the bottom of the tank and would periodically dash about the bottom of the tank trying to dig into the stones.


Water parameters are fine

Ammonia 0.00ppm
Nitrates 0.00ppm
Nitrates 5.0ppm

PH 6.8 (Low ??)

A water change was carried out yesterday and I noticed the temp was down to 18c (NORMALLY AT 20C)


His general appearance is clamped fin/curved spine...... The other fish are going to him concerned he may die and they eat him



What could be the problem and is there any solution ??

My dad doesn't have a hospital tank to put it in


Any help please......??

Thanks


Traceyb

 

[N0body Of The Goat]

The temp of 18C this morning should not be an issue, that is the lowest suggested temp. Any chance the new water was colder than this, which would have shocked the fish?

A 30l Biorb is so unsuitable for Zebra Danios on so many levels...

~30cm of adult fish in 30l of water is a gross bioload overstocking, even a group of sedate fish would need 60l of water at the very least.

The very design of Biorb tanks gives them much less surface area for gaseous exchange.

Even if ammonia and nitrites are kept at zero, the nitrates will go sky high (5ppm is highly unlikely, the nitrate test is very unreliable) even with 50% weekly water changes under normal circumstances. At 300mg/l this becomes toxic for most fish, even hardy Zebras... and if those fish are getting enough food the true nitrate levels will raise to toxic levels, unless the tank gets multiple big weekly water changes.

These fish, despite being relatively small, are one of the most active fish commonly available. They really do deserve a 4-foot tank and even in that space they can zip from one end of the tank to the other against a strong (>8x true water turnover) upper water current in less than two seconds (possibly even <1 second).



A curved spine could simply be a genetic deformity, these fish are bred in huge numbers. It could be as a result of deformed growth in that tank, if bought as a baby. It could but hopefully is not fish TB.

How big a water change was done yesterday? If <75%, I would net the fish into a bucket with some of their current water; empty the tank of water; refill with similar temp; acclimitise the fish to the new tank water as if just brought home from the fish store; net the fish back into the tank; topup the tank to account for lost acclimitisation water. Then keep a closer eye on the fish than normal to see how they respond.

 

[TraceyB]

He said it was only about a 10% water change (left the water overnight) I know the fish are not suitable, I may take them off his hands and try and persuade him to get something more suitable....... But what fish really is for a Biorb..??


TB is that not contagious?

 

[N0body Of The Goat]

Fish TB is highly contagious.

As for suitable fish for a 30l Biorb, hmm, not easy but a few that spring to mind are...

A Betta
or
6 Celestial Pearl Danios(?)
or
6 Ember Tetras(?)
or
6 Chilli Rasboras(?)
or
3 Sparkling Gourami(?)
or
A few Dwarf Puffers(?)
or
A few Dwarf Gobies(?)

I'm really not sure if any of the above schooling fish would be ok long term, by far the safest responsible choice is the single Betta splendens, definitely needs more input from others.