Help - My Fish Are Dying!

[alanmunday]

Hi everyone I hope you can help me.
 
I inherited a Biorb 60 litre tank and have had it up and running for several months in its new home although it was running for 2 years before that. I transferred it with 50% of the original water and filled the remainder with treated tap water.
 
The tank came with a 1 year old Peal Gourami
 
Tank size: 60 litre
pH: 7.4
ammonia: 0.25 ppm
nitrite: 0
nitrate: 40 ppm
kH: ?
gH: ?
tank temp: 24.5

Fish Symptoms (include full description including lesion, color, location, fish behaviour): 1 platy had been very lifeless and lying on the bottom of the tank for some time only coming up for food - then noticed a 1 deed platy last night and another this morning

Volume and Frequency of water changes: 10 litres every 10 days

Chemical Additives or Media in your tank: A typical biorb set up with biorb filters and ceramic media

Tank inhabitants: 1 Pearl Gourami (original fish), 4 Platy (2 have now died), 6 Neon Tetra (can only see 2 now)

Recent additions to your tank (living or decoration): The Pearl Gourami has been in the tank for 2 years, Platys were added 1 month ago and Neon Tetras 2 weeks ago

Exposure to chemicals: None

Digital photo (include if possible): 
 
I hope you can offer me some advice to turn things around - I have another biorb 60 litre tank which has been running without problems for 2 years plus.
 
Many thanks
 
Alan

 

[techen]

As I remember the bio orb has very poor filtration and this could be the cause.  Also the pearl gourami I wouldn't have put in a tank of that size. They claim to say there 60litres but there infact around 40 litres when you remove the space they've taken up with useless things. I think the new tetras have knock your bioload out of sync and yea killed the fish via ammonia thats now been cleared up by waterchanges/filter.
 
Is there any signs of red gills, rapiding breathing? 

 

[alanmunday]

The two platys that are left are certainly gasping for air as they are spending all their time at the surface!
 
I was today planning to remove the Pearl Gourmai to a friends 600 litre tank!! - This was already planned would this be a sensible move? 

 

[star4]

If possible then yes move the fish. The main problem with the Biorb is the small surface area not leaving enough room for gas exchange. If possible add an extra airline to get more air in the tank see if this helps the platy's. Also with any reading of ammonia do an immediate water change to remove this.

 

[alanmunday]

The gourami has been removed and the few remaining fish already seem happier.
 
I think he may well have been intimidating the other fish

 

[star4]

You still need to do a water change to remove the ammonia - but good news the fish seem happier