i have a feeling this is going to be a long post but i'm just trying to provide as much info as i can...
so i've had my 15 gallon tank set up since the thursday before last. in it are 3 corydoras panda and a gourami. they all seem happy and well but something has been bothering me. i've noticed the corys sometimes scratch on the bottom of the tank or on decor. i've heard this is a sign of parasites or some sort of irritation but i can't see anything on the fish to suggest they're sick, except for the scratching. most of the time they are swimming around happily and eating stuff.
this evening i noticed one was scratching a lot and looked quite annoyed. I did a 25% water change. i've been doing water changes almost every day since i set the tank up because i don't know what's going on with the cycle and i want to make sure the tanks clean. i want a nitrite/nitrate/ammonia text kit but i haven't got round to buying one yet. i've been testing the pH every day too.
anyway the corys are still scratching a bit after the water change. they don't do it all the time and in fact i thought it'd stopped altogether before i noticed one doing it a lot this evening.
here's some info about my tank
tank size: 15 gallons
pH - 7
temperature - most of the time 25-26 Celsius (except after water changes its a bit colder)
substrate - bare (i'd like to put some gravel or sand in, but not until the tanks been set up for longer)
tank's been set up for 12 days
decor: driftwood with large java fern growing on it, floating elodea, ceramic log
filter - homemade using the plastic v-insert from a breeding trap, some filter wool and an airstone (it provides a fairly gentle current and is still effective)
i doubt the following will have any bearing on what could be wrong with my catfish, but i'll mention it anyway.
recently i had to euthanase a fish and i have another fish who is on deaths door who i might also have to euthanase. i don't know what was wrong with either fish but they definitely have/had the same thing. the one i euthanased was a golden barb i'd had for years and he'd always been one of my hardiest fish, withstanding pretty much anything. for a while he shared my tiny 6 gallon tank (which was horribly overstocked but incredibly, maintained itself) with a betta, some corys, two gouramis and my angelfish. after a while he got too agressive towards the other fish and i had to move him into my outdoor pond. i didn't expect him to adapt to the freezing temperature so well or so quickly.
well he'd been living in my outdoor pond for at least a year and when i was setting up my 15 gallon a few weeks ago, i decided to try to catch him so i could put him in the tank while it was cycling.
when i did catch him, i discovered he was not at all well, however. one of his eyes was bulging and there was a white fleck in the cornea that kind of looked like fungus exept it was INSIDE the eye. he was also breathing very fast and not swimming much, just sort of hanging around the bottom of the tank i put him in. i didn't know what to do so i put him back in the pond.
a few days before that i'd noticed my angelfish wasn't well. he's normally a very strong fish and he was acting perfectly normal, but he was producing excess mucous - i could tell because bits of detritus were sticking to him and hanging of his fins. also, one of his eyes was bulging at one side and there was a fungus-like blob in the cornea. just like the barb had.
i'd noticed for some time that the silver rim that runs around the very outside of his eye (not sure if you know what i mean) had been bulging over into the reddish-tinted ring around the pupil (i'm not sure if you call that the pupil in fish? hehe) but i'd never worried about the odd appearence of that eye before.
anyway when i moved the gourami and catfish into my newly set up tank, i converted the old tank into a hospital tank for my angel and treated him with melafix for a week. it seemed to help - he stopped producing too much mucous and was acting normally, although his eye didn't improve.
the day before i was due to stop treatment, i caught the poor little barb from the pond again. i thought maybe i would put him in with the angel and treat for another week to see if it helped. but when i the state the barb was in i realised there was no hope for him so i put him in the freezer....
anyway since then (a few days ago) my angelfish went from seemingly fine to a similar condition to the barb. i noticed it first last night - he was pretty quiet all day, but when i got home that evening (i'd turned out the light before i left) i actually thought he was dead at first. he was probably half asleep still, but if i'd left the light off i reckon he would have died. he was barely breathing. he did recover somewhat but since then all he's done is hang around the bottom of the tank, breathing really fast. this morning when i was feeding the other fish when he saw me come into the room he struggled to his feet (as it were) and begged feebly at me through the glass. he's such a fighter. i fed him and he seemed as greedy as ever. but then he just sank to the bottom again, too tired to get up to the surface to eat the last of the flakes. poor little chap.
i've left the filter off in the tank because the current (gentle as it is) seems to distress him.
so i don't know whether that could have anything to do with my irritated corys. it probably doesnt. but i thought i'd better mention it anyway. after all they did share a tank with the angelfish for a few days.
i've also wondered if the elodea or snails in my pond could be carrying something. because elodea seems to require very bright light to grow, and the lighting in my tanks is dim (or, you could say, nonexistent) i regularly replace the floating elodea in my tanks with fresh, bushy, green elodea from my pond, which has been exposed to the light. occasionally there'll be a little snail attached to one of the pieces. also, recently i've noticed some of my elodea leaves turning a nasty maroon colour, and funny little things that kind of look like buds on the plants. its hard to explain. but i've never seen either of those before. when my elodea starts to die it just goes brown, not maroon!
anyway sorry for such a long post and i hope someone can help me because i'm trying really hard to make my new tank work and i don't want it complicated by sick fish :(