Hi Hoppo and Welcome to TFF!
Well, we've seen dozens of serious problems of this sort happen in recent years, so you are not alone (and it often happens in the same way!
)
To be Fishless Cycling would mean that you were dosing household ammonia directly to the tank water. Were you doing that? (it would mean pretty quick death if you subsequently added the fish you describe!)
Unfortunately, the collection of fish you have listed means that the tank has been immediately overstocked, even for a healthy running tank with a working biofilter, but of course yours can not be a running tank yet as there is no biofilter (these take a couple of months usually before they are ready for fish.)
The best action in these cases is to attempt to find an LFS (local fish shop, either the one where the fish were purchased or another one) or a hobbyist who will take the fish and hold them for you until you can get your tank cycled. My recommendation goes in this direction because the stocking amount would need to be reduced in this way regardless, so as long as you are looking then it would make sense to attempt to move the entire stock.
By the time you read this the 10G will already probably be building up enough ammonia to be causing permanent damage to the gills. Your first action will need to be large daily water changes of about 75% of the water, using good technique (which means the return tap water needs to be treated with a good conditioner to remove chlorine/chloramine and roughly temperature matched (your hand is good enough for this.))
Once that urgent action is taken, you will need to obtain a good liquid-reagent based test kit if you don't already have one. Most of us like and use the API Freshwater Master Test Kit. You will need to learn to use it (you can test your tap water and post up the results for the members to see.) The water test kit will allow you to better gauge the effectiveness of the water changes you are doing. Until you can find the new temporary home for the fish, you will be in what we call a "Fish-In Cycling Situation" (not a good situation for fish, for whom it is life and death.)
Your goal in a Fish-In cycle is to use your kit twice a day to help you gradually get a feel for what percentage and frequency of water changes will keep both the ammonia and nitrite(NO2) concentration below 0.25ppm as a maximum. In anything more than an 8th to quarter stocked tank, this can be near impossible as the weeks progress. This is why your other goal of finding the temporary home is so important.
Now one thing you may have going for you is that the overall volume of water you need to move about the house is not as much with a 10G and your boys and wife may be motivated to help, once they understand the situation.
Let me explain the "why" part: When fish move water through their gills, they extract oxygen but they also give off significant amounts of ammonia (NH3) directly into the water. Fish waste, excess fishfood and living plant debris are all composed of organic molecules that are broken down by heterotrophic bacteria (not the ones we want to grow in our filter, those are different) into more ammonia. Ammonia, even in tiny concentrations, causes permanent gill damage leading to shortened lives or death. In nature, the ammonia is carried away by thousands of gallons of water every few minutes.
In the aquarium hobby, we have some magic going for us. It is called the "biofilter" and is one of the three main functions of the filter systems we put on our tanks. Certain of the media in the filter makes a good substrate for "autotrophic" bacteria and one species of this type (Nitrosomonas spp. or "A-Bacs" for short) can oxidize ammonia(NH3) in to nitrite(NO2) and gain energy for its own existance in the process. The A-Bacs can thus clear the poison ammonia from the fishes environment.
Unfortunately, the nitrite(NO2) that the A-Bacs create is an even worse poison for our fish. Nitrite(NO2), even in tiny concentrations, suffocates the fish, causing rapid nerve and brain damage leading to shortened lives or death. The actual mechanism is that the NO2 can attach to the fish blood hemoglobin protein (where oxygen should) and when it does that it causes a complete destruction of the red blood cell (the blood actually turns brown.)
In a working biofilter, we grow a second species of autotroph (Nitrospira spp. or N-Bac for short (for nitrite oxidizing bacteria)) and this bacteria can convert NO2 into nitrate(NO3) which is not great but is no where near the poison that nitrite or ammonia is as far as the fish are concerned. We can remove the nitrate(NO3) (and many other bad things) via the standard weekly water change with a gravel cleaning siphon.
The biofilter has been the core magic of the hobby for nearly a century and getting lots of hands-on experience in creating, maintaining and understanding them is what begins to turn a beginner into a good aquarist. Since the biofilter is a living thing, it is tricky to create and maintain sometimes. Without a previous filter from which to get live bacteria of the correct species, it can take up to two months or more to grow enough bacteria to begin a first fish stocking of the tank. Old hobbyists with other tanks can borrow their own bacteria and get a new tank going in only a week or two.
Let me know if you have questions or if this doesn't make sense. I hope it helps explain the "why" of the filter cycling. The two bacterial species are very slow growers and there is lots of mis-information about to feed the hopes of impatient people or to try to pretend that the fish are not hurt by inadequately filtered water. The TFF beginners group here though are great at helping and they will be your friend!
~~waterdrop~~
