I have two long finned blue danios. I don't know their genders, but I've noticed that one is larger and fatter than the other. Is this a girl, because I haven't noticed eggs in the tank, and she's been like that for several days. I should describe my tank. I have a ten gallon, (which will be upgraded to a thirty-five+ with in the next week). In this tank I have one gourami, about 4 and a half inches, two more gourami, of a differant variety, (male and female, about three inches, one catfish-type fish i got from petsmart, about four and a half inches, one fish labeled as some kind of shark, (not really a saltwater shark, almost like a bala shark, who is about four inches, one silver molly, about 1 and a half inches, one female guppy, the same size as the molly, two long finned blue danios, and three giant danios. They are all healthy and have never "attacked" eachother, like some people have warned me they might. Their water is filtered and they have an air bubble thing, also it's heated. What I'm worried about is that one of my longfinned danios is fatter than it was two weeks ago and it spending a lot of time at the bottom of the tank, this is a problem because the catfish-like fish spends all it's time there, and it's large. Even though there have never been problems before, i'm worried that the catfish-like fish (named Corey) will attack the long finned danio. Why is the danio spending so much time at the bottom of the tank? I kinda lied when I said there were no attacks.... I don't know for sure what happened, but I HAD a male fancy guppy that, well, vanished. Corey is the only fish in the tank with (i think) a mouth big enough to eat the poor little guppy, (it was like an extra-small one). Oh. i'm sorry this took so long, and i you read this far, I hope your eyes don't hurt.... One other thing, this setup (of my tank) has been this way for eleven monthes now. And incase you got confused, my questions: Is my longfinned danio in danger? and Why is it so fat?

if it is in danger, can Corey be put in with a three inch oscar and a two and half inch jack dempsey?

thank you

We have to determine which species Corey is and why your danio is enlarged. If you can send a small photo of Corey, I should be able to tell you more. You might also look through a fish encyclopedia at your local pet store for a match (or find another for sale with a label, assuming it's correct!). Many catfish will eat fish, especially when they grow older, or if the fish is sick and just sitting on the bottom.

Your fat danio sounds like it could have an internal bacterial infection such as dropsy or fish tuberculosis. A photo of her/him too would help. When egg-laden, a danio is just slightly enlarged. If really big, it's probably something else. I list reasons a fish may be fat at http://www.fishpondinfo.com/health4.htm#fat for more information. Your tank is overcrowded so bacterial problems are also more likely. Until you get that larger tank, try to do 50% water changes once or twice a week.

The sick danio (sick danios usually lie on the bottom) could possibly be eaten depending on what species Corey is. Not knowing what Corey is, I can't say if he'd himself be safe with the oscar and Jack Demsey.

I think Corey is called a pictus catfish. He's blueish-greyish and his whiskers are a little more than half the length of his whole body. He's covered with dark spots that seem like poorly drawn diamond shapes. Sorry I don't own a digital camera, or even a scanner. I remembered the name when i saw it on another site about fish.

Is Corey a type of catfish that will eventually eat his tankmates? I didn't think to ask this when i purchased him. How large would a fish have to be in order to be safe in the same tank?

if my danio might have an infection, can i still leave her in the same tank? Did she already infect my other fish? Shouldn't it be harder for differant types of fish, such as the gourami, to catch an illness from the danio?

I was looking really closely at my tank, and I noticed that the danio wasn't staying at the bottom all the time, just a little, then going back to the middle and top. In fact, i twas only yesterday that she was at the bottom mostly, maybe i just saw her when she was bored with swimming?

The filter I have is for up to thirty gallons of water. Wouldn't that keep the water in a 10 gallon clean enough?

Tomorrow I am going to move my fish to a 55 gallon tank. The thing is, this tank's occupant will switch places with my fish. The occupant is a hamster. I plan to wash the tank completely, several times in the course of at least three hours. I'm going to use a cleaner sold at a pet shop, that claims to be safe for animals. One of my ways to check if the water is clean (when i've done this kind of thing before) is to fill up the tank and make sure there are no floaties or junk, then drink a cup of the water. I know that sounds nasty, but i'm thinking if the water is clean enough for me drink without ending up in the emergency room, it's safe for my fish.
Oh, and i'm going to leave the tank set up for six hours, with the filter running and everything before i let my fish in. Any advice on how to make this tank change any safer?

Once i put my fish in the 55 gallon tank, is it possible to add new fish (without over crowding), after a while? How large can they be?

Can I let my oscar and Jack Dempsey visit with these fish? I used to let my betta and gourami do that, they seemed to like each other if they didn't have to live together.

Sorry to ask so many questions, in case you haven't already figured out, I haven't really kept these many fish before.

Thank you for replying to my previous post, you are wonderful!

If Corey is a Pictus catfish, then he may eat small fish as he grows. If their sizes are similar, he could go in with the oscar and Jack Dempsey. This site says they grow 6-10" (they list two kinds) and will eat fish under 2.5" long:
http://www.mongabay.com/fish/pimelodidae.htm (search for Pictus for the correct section). I actually got one of those years ago from a store before I knew much about fish and put it with goldfish (they said they got along). The fish shredded the goldfish fins immediately. I put him in the bathtub overnight to return; the tub drained overnight (hey, I was a dumb kid!); the stranded catfish was alive in the morning but died before I could get back to the store.

"Is Corey a type of catfish that will eventually eat his tankmates?"

Yes.

"How large would a fish have to be in order to be safe in the same tank?"

At least 2" long. Danios are smaller than that.

"if my danio might have an infection, can i still leave her in the same tank?"

That's up to you.

"Did she already infect my other fish?"

Yes, they're already exposed.

"Shouldn't it be harder for differant types of fish, such as the gourami, to catch an illness from the danio?"

Sometimes certain problems are more common in one species than another. My 14" pleco has never shown any problems even when he was a baby in a tank full of ick and now in a tank with danios with severe tuberculosis.

"I was looking really closely at my tank, and I noticed that the danio wasn't staying at the bottom all the time, just a little, then going back to the middle and top. In fact, i twas only yesterday that she was at the bottom mostly, maybe i just saw her when she was bored with swimming?"

Or, maybe when tired. Healthy danios spaz all over and rarely rest on the bottom.

"The filter I have is for up to thirty gallons of water. Wouldn't that keep the water in a 10 gallon clean enough?"

If the tank weren't overcrowded, and the filter's of good quality and kept clean, and you do water changes as well, yes it would.

"I know that sounds nasty, but i'm thinking if the water is clean enough for me drink without ending up in the emergency room, it's safe for my fish. "

Not necessarily. Instead of doing that, bleach the tank to disinfect it. Fill it with water and a few cups of bleach. Let it sit for a while (at least a few hours but a day is better). Then, drain that and refill with fresh water and a double dose of dechlorinator. Let it sit again for an equal amount of time (a day is best). Then, get rid of all that water again. Add rinsed gravel, refill, set up the filters and heater, aerate, add additives (dechlorinator, salt, etc.), etc. and add the fish a day later. See http://www.fishpondinfo.com/fcare2.htm#tear for more details.

"Oh, and i'm going to leave the tank set up for six hours, with the filter running and everything before i let my fish in. Any advice on how to make this tank change any safer?"

Let it run for a day if you can before adding fish.

"Once i put my fish in the 55 gallon tank, is it possible to add new fish (without over crowding), after a while? How large can they be?"

Yes. I would wait at least a month. Stick to fish of similar size.

"Can I let my oscar and Jack Dempsey visit with these fish? I used to let my betta and gourami do that, they seemed to like each other if they didn't have to live together."

I don't think that's a good idea. Not only will the oscar and Jack Dempsey eventually want to eat those smaller fish, the stress of moving around and chance of disease transfer is not a good idea.

thank you thank you thank you! I took your advice on the bleach.

Oh, and in case you are wondering, I didn't drown the hamster or anythng. I got him a new cage, not a tank. He doesn't seem too happy with that.... So i'll have to clean the 10 gallon and put him in there.

thank you again

Of course I didn't think you drowned the hamster! They make some nice hamster cages that look more like bird cages. They do cost a lot though. The 10 gallon tank is pretty small and has poor air circulation so I hope you can find a better home soon.