Ok guys, here's the deal...about 2 weeks ago, i purchased a red tailed catfish.. he has a 15 gal. tank....he had gill curl one side, he didn't eat, and wasn't very active..now, he still has gill curl, already started eating but stopped 2 days ago and hasn't eaten again, and started hiding in a jar that i placed but doesn't come out even at night and there are no lights..I asked for help in my last thread and so far these are the things i have done,...I change about 10% of my water once a week, <Not enough. Try for 50% in this small tank, with this hue bioload.> i siphon any feces that i see, <RTCs don't have solid feces... is a liquid... so you need to clean the gravel well whether or not you see waste.> and i've added a water plant to help cycle the tank <Not going to do anything here.>,..the water in the tank is clean and clear although i don't know my water params because i don't have a water test kit.. <It's not clean if it's not cycled. It's toxic and it's causing him to be miserable.>I doubt i will obtain one cause my dad won't buy one..it costs 900php(20$)..which might not seem much to you guys but very pricey for my dad i guess... <How does he feel about the two or three grand, at minimum, it's going to cost to house this fish? The huge electric bills that come with moving 10,000 gallons of water per hour? The food bills? This is a mistake. Please return the fish.> everyone please help in answering my questions...will the aquatic plant help cycle the tank?? <No.> is ok to not own a test kit as long as i keep the water clean and change water frequently?? <No.> how frequent may i ask will be ideal?? <It won't matter in a month... will never be clean due to the large bioload in a tiny, tiny system. And the fish will probably be dead.> i saw some water treating solutions and whatnot for sale at the pet store, do these help cycle the tank?? <No.> and when you change water do you add any solutions like anti-chlorine or aquaruim salt?? <Always use dechlorinator, don't worry about salt. This fish has problems salt won't fix.> our tap water has chlorine so i add anti-chlorine to the water i use for changing...and also advice, opinions, and criticism are all encouraged..many thanks everyone!!!!!