Flashing loaches - no other signs of illness

[tmcmullen]

I have an established 75 gallon tank with 6 clowns and 2 Yoyo loaches. I had a black ghost knife fish in the tank for about 4 to 5 months, but it died suddenly without displaying symptoms of illness. A few days later I lost a yoyo loach. The yoyo's have been acting funny lately, but I figured it's just their loach-like behavior. They would hang out at the corner of the tank either right-side-up or Upside-down with their nose in the corner as if their nose was steading them as they all hung out there diagonally. Very strange. At times I thought one was dead, but then when it saw me it would swim away as if everything was fine.

Yesterday I noticed one of the yoyo's and one of the clowns scratching on the rocks at the bottom of the tank. The Yoyo was scratching like mad! I don't see any spots, I'm familiar with Ich and I'm confident it isn't ich. Over the last month I've noticed the clowns and yoyos will scratch now and then, but this is the first time I've seen them scratch so fiercely, and after the recent deaths in the tank I'm concerned that there might be a parasite of some sort that I can't see in the tank.

The parameters of the water are good. The PH is 7.6, which is normal, the Nitrates are very low - under 10, Nitrites are 0, Ammonia is 0, Chorine is 0, all other parameters are in the "safe" zone.

Does anyone know what I can do to wipe out whatever is affecting my fish?

Thanks!

Teri

[chefkeith]

Are you still salting the water?

Did you ever get a TDS meter? If so, what is the TDS of the tank and of the tap water?

How often do you do water changes? How big are water changes?

Has the water temperature dropped suddenly?

Is the tank planted? If so, tell me about the lighting and if you have airstones running at night? Is the pH the same in the morning and at night?

[tmcmullen]

Chefkeith, I did not buy the TDS meter, but I stopped salting the water. I have been doing 1/3 water changes every 2-4 wks. I try to do it by the 3rd week, but sometimes the schedule gets so busy I push it to 4 wks.

I have just a few plants, and most of the plants in the tank don't do very well. I pull them out when they get down to just a few leaves left, but I also cut the dead leaves/branches so they don't pollute the water. The lighting is a regular flourescent bulb, not anything special. I keep the light on during the day, and a moonlight (blue LED lights) at night. Airstones line the back wall and run all the time.

I never thought PH would fluxuate day to night, so I haven't checked for a difference.

I forgot to mention earlier that I recently bought liquid plant food and started using that about 3 wks ago.

[chefkeith]

My advise is the same as before.

Smaller, more frequent water changes. Twice weekly 20%'s changes would be ideal. While adding the water back slowly.

Get a TDS meter. You need to avoid dropping the TDS too much when you do water changes. Even if the nitrates stay low (because of the plants), other minerals will accumulate quite quickly due to evaporation, fish food, rocks leaching, adding fertilizers, ect, ect.

I think your fish have osmoregulation problems because they were accustomed to high TDS salted water in the past.

[tmcmullen]

Okay, thanks Chefkeith. So I guess it doesn't look like a parasite afterall.

[chefkeith]

I just looked back at an old thread of yours. Do you still use well water that uses water softeners on fish tank?

If so, that could be the problem. You really need to monitor the TDS closely and/or start using RO water.

[tmcmullen]

I have well water, but I bypass the softener when doing water changes, so that shouldn't affect the water.

I'm looking for a tds meter. I will get one and check the levels.

[starsplitter7]

I found my TDS meter at a drug store (Walgreens) for $20. No frills, but works great.