Pics of potentially doomed fish

Godspeed little sacrifishies.

Its the neons who are suffering.

Any *helpful* suggestions?

Prime? I'm not sure whether it will affect the cycling process, though..

The thing to do is get some established media into your filter.

Coco.. there are some short cuts but certain things can't be ignored. The Prime should help but you've got nothing in there helping defeat what the fish are giving off. If ya got time, drop on in and I'll give ya enough seeded floss that will assist.. no guarantees but it beats watching them get poisoned! I'll be here all day.. bill

I'm just throwing this out as I've no clue what your readings are.. but .. get some buckets of water and do some massive w/c's that have been treated with prime.. your fish are probably dying of ammonia poisoning... The seeded floss would have converted that immediately into the next stage and the stage beyond that... You'll still be forced to do even more w/c's until you get some balance in your tank. Just how many fish have you added? Bill
P.s. Some of my advice might be of no avail and hopefully someone can chime in ... Worst case, after your w/c's, (50%), pull the fish and get them to an established tank. I can free up a cycled 29 but don't know your fish load. Bill Still

I agree that ammonia poisoning is the likely culprit. Prime should be fine and can even help the situation by detoxifying ammonia.

Here is what you can do:
1. Get established filter media - this will contain beneficial bacteria that will convert ammonia to nitrite and nitrate
2. Add a sponge filter - if it is an established one this can accomplish step 1
3. Stop/restrict feedings - this will reduce the amount of ammonia being added to the system
4. Do large water changes - this will reduce ammonia levels

Once your tank is stabilized do this to add new fish
1. Move sponge filter to quarantine(QT) tank
2. Keep new fish in QT tank for 2 weeks minimum, 4 weeks is ideal
3. Enjoy your healthy established aquarium

Update.

No fish fatalities today.

I went to Skoolz after work and was kindly sold a huge sheet of muck filled filter for $6.

Came home and took out 95% of the water and as much dead plant matter and dirt/food as possible. Took apart my filter (pita) and cut up this huge slab of blue filter and packed it in there in all three layers of the baskets. Kept the two water polishing pads in the remaining brown slime in case needed for future use.

Filled everything back up with prime water. I see that the fish are more active. Haven't fed them today.

My sand gradation has gone out the window but I can worry about that another day.

*face palm* Fishless cycle would have been much more humane.....

Well, continuing on then...

Another huge water change today. Got rid of most of the hornwart as that didn't seem to be getting any better (re falling to pieces)

No addl fish fatalities.

All essence of sand gradation completely gone...However, am very thankful that no bucket lifting is involved.

Looks like ya might be over the hump with that crisis