Sick Zebra Loach

Question
We have had two beautiful zebra loaches in our very stable 50 litre tank for over 2 months now.  In summary, due to a lack of foresight, we ran out of our usual dechorinator (Tetra AquaSafe)and used Sera Aqutan for two water changes.  The result was that the largest loach reacted very badly. He has paled in colour, swims either very erratically as though epileptic, or just flops lifelessly in a heap somewhere for long periods. As the smaller loach did not seem so badly affected, we initially thought he could just be ill and he eventually recovered in around 10 days, however the behaviour has restarted since the second water change and this time both loaches are affected although the smaller one not as extremely. All our other fish are fine (barbs, harlequins, tetras). This coincided with a filter change and the ammonia levels increased to a safe but present level. We have carried out a 20% water change today using our original decholorinator and Sera Nitrivec biostarter for the ammonia, but after two hours he still looks miserable. Is there anything else that we can do or use to help him recover quickly? I would be really grateful for any advice!

Answer
Hi,
Sometimes it is not a good idea to mix two dechlorinators together. Although, i dont feel the dechlorinator is the problem. Your fish seems ill and it sounds water quality related. When you say the ammonia levels increased to a safe level do you mean the ammonia went from zero? Ammonia should always be at zero in an established tank. I would add some aquarium salt to the tank. This may help him recover. Keep doing daily water changes to get the ammonia level down as this is probably the problem.

Regards,
Chloe.