I'll try to not come across as rude/mean/bossy, as it's never a good way of communication.
1) I understand not wanting to add chemicals to the water, especially if you don't understand what it does. It is important, however, that there be no chlorine or choramine in the water, because it kills micro-organisms and can be toxic to tank occupants. If the beneficial bacteria die, it can prevent your tank from cycling properly, and thus the bacteria can't deal with the nitrate/nitrite/ammonia build up. A cycled tank is a tank that takes less effort to maintain healthy, happy occupants
Hopefully it helps if you understand what a dechlorinator is made of, and how it works (the following I found on the net):
"There are many products sold for aquarium use that are specifically intended to remove chlorine. Several brand names include: Prime, AmQuel, AP Tap Water Conditioner, Aquasafe Plus, and many more. These all include Sodium Thiosulfate, which reacts with the chlorine (or the chlorine portion of the chloramine) to form harmless chloride ions. The chlorine is completely and totally removed. This reaction happens instantly. The tap water doesn't need to be mixed with the dechlorinator for any amount of time before adding it to the tank. It's safe to just add the dechlorinator as you add the water into the tank.
There is one potential problem if your water is treated with chloramine. As stated above, the dechlorinator reacts with the chlorine portion of the chloramine. The chlorine is eliminated, leaving the ammonia free in the water. As you hopefully know, ammonia is toxic to fish, even in low levels. So, if you use a simple dechlorinator that only contains sodium thiosulfate, you are solving one problem (chlorine) and creating a new problem (ammonia).
Lucky for us aquarists, our aquarium product companies have a solution. Many of the dechlorinator water conditioners include chemicals to convert the ammonia into harmless ammonium. Look a a few labels. My favorite one, Seachem Prime, states: "Removes chlorine, chloramine, and ammonia". Others that I'm sure handle the ammonia include Tetra "AquaSafe NH/CL Formula", Jungle's "ACE", Kordon's "AmQuel", and Kent's "Professional Ammonia Detox". If the label doesn't specifically mention that it neutralizes ammonia, then don't depend on it to safely treat water containing chloramines."
Dechlorinators are also quite cheap - I paid $8 for a bottle that will treat 500 gallons.
2) Plants will definitely help keep your tank cleaner, as they compete with the algae for nutrients. They also will help with nitrates and A LITTLE bit of ammonia. If your axies are destructive, you can always place them in a pot or yogurt container to keep them safe. Have you tried floating plants? Those can't really be disturbed and will also decrease the amount of light in your tank - axies prefer less light because they do not have eyelids - and less light means less algae that require light to grow.
3) I'll admit, when I was younger, I hardly did water changes with my fish... like you, every couple of months. But then I learned from people around me, from people who have been keeping fish for over 30 years! Their advice may seem harsh, but it's because they're passionate about their hobby, and considering the hobby involves other living things, its important to consider what others have to say
Anyways, now my aquarium fish are happier, live longer, have better color and more importantly are healthy. Keep in mind that your animal may be sick, but in the wild, sickness is a sign of weakness. It's natural for animals to hide their weaknesses for as long as possible to prevent being picked off. That's why when cats are discovered with illnesses it's almost always too late to completely heal them, because they're capable of hiding it past the point of being able to heal.
4) Hopefully you decide to change your water more frequently and add a dechlorinator. I bet you'll see changes in your axies behavior for the better
As for the sponge filter, when you clean it, clean it in some tank water in a container by genetly squeezing it out. Tap water will kill your beneficial bacteria and potentially make your tank have to cycle again.
5) I realize some people will point things out strongly, say you should do X. Keep in mind this forum is full of dedicated people that want the utmost best for these critters. They're upset that you didn't think to do your research, however by joining this forum hopefully it's a sign that you care about your creatures too. Just because they're surviving under conditions Y doesn't mean that they wouldn't be much better off in conditions Z, so please take these suggestions to heart, because they're talking from years and years of experience, experimenting, and research
