First of all, good for you for keeping them in a big tank like they need. I'm so sick of telling people they can't keep them in 10 gallon tanks with redtails and rainbow sharks, its unbelievable. Kudos :)

If it was right after a waterchange, that this happened, it is probable that it has something to do with the new water. I doubt their gills got clogged...bala sharks are pretty sensitive to water params, and gasping can be a sign of poison, but along with other things. I suggest you test your tap water for ammonia, nitrite and nitrate. Test for pH too, just incase your water supply company decided to meddle with it (this happened to me recently, but out of pure pure luck I tested the tap as they were changing it...and I hardly ever test the tap pH). If you have any way to test your water for chlorine, definately do that. Water companies often add a strong dose of chlorine to clean the water every once and a while, so if you can't test for chlorine or other metals, add a huge dose of water conditioner to your tank and call to see if you can find out.

I'm sorry about your sharks :( Bala sharks truly are magestic creatures that rarely find knowlegable owners with suitable living quarters. Yours did, but its a shame they didn't make it...

It certainly looks like one of those unexplained water problems caused by some thing totally out of your control.

Keith

I have had fish gasping up at top after a water change, too. First time this happened was about 5 years ago after a water change (just like yours) and gravel cleaning. My angels and gouramis and blue rams were really in distress by the time I found them. I set up an air pump and air stone. Oxygenating the water did the trick. Unfortunately I lost both blue rams, but the larger fish came back.

Sometimes I think it may also be stuff that gets stirred up from the gravel.

I've used this solution any time I've seen the fish behave this way (which is always after a water change) - which maybe has been 1/2 dozen times since 5 years ago.

Not sure if this is what happened in your instance.

Keep an air pump, tubing, and airstone at hand just in case.

The quote about the funeral was really funny. Its just the way you said it. I give all my fishes their proper burial as well.