Guppies dying in 10-gallon with killifish

I've gotten a small group of guppies a few weeks ago (1 male, 3 females) and have two of them die as well as an old male guppy I had in there. The new male died but was acting slightly off (staying near the top behind plants and not really eating after a few days of being comfortable). I didn't see any real injuries except a single white spot on the edge of one of his gills which I assumed was an injury (all were healthy when I got them and no other fish showed that sign). The old male guppy died from seemingly old age. I've had him for over a year and his spine had deformed after some time but I found that he was losing his back fin (he was a lyretail guppy) and was concerned as to how.

After watching the tank for a bit I found that the male killifish would occasionally chase and nip at the guppies. He's also old and on his way out but I'd never seen him do this before until a few days after I added the guppies when I noticed the old guppy missing part of his tail. It wasn't often and appeared to be a one-time thing since I didn't see it again and the guppy had been right in his face. Now that I've lost both male guppies and a female guppy (I wasn't home but my sister said its fins were missing, though she doesn't know how long it's been in there and the killifish was eating it when she found it) I'm wondering if the killifish is the culprit. Are killifish known to be fin nippers or aggressive when in a tank with guppies?

The 10-gallon has been running for over a year and water change day is tomorrow so I will check my parameters then (I'm not home today until late so I won't have a chance). The last time I checked it about a month ago, it was 0-0.25 ammonia (a false reading because the tap has 0.25 ammonia), 0 nitrite, and between 10-20 nitrate. Water changes are once a week 30-50% along with some light trimming of moss and vacuuming of loose debris. Only inhabitants are the male killifish, 8 dwarf emerald rasbora, and what was 5 guppies and is now 2 female guppies.

 

Depends what type of killifish you have

 

Depends what type of killifish you have

Gunther's killifish. Nothobranchius guentheri. And if he's the problem would moving him to a 10-gallon with platy and ember tetra be better? I've also got a 60-gallon with rainbows, cory, neon and serpae tetra. Or I can do a move of the remaining guppy to those tanks if not.

 

I separated the last two female guppies into my other 10-gallon and may have discovered part of the problem. One of them had fry. I caught the killifish hunting them down. Caught what I could (8 baby guppies) because I do want to have them survive and moved them into the tank with my blind fish who couldn’t eat them if she tried. I’ll continue to keep the guppy separate from the killifish until he does pass from his old age then I’ll move them back.

 

Its usually not the result of your own aquarium but where you got the guppies. Assuming you got them from a petstore, theres your problem. If your serious about guppies you should buy them online from a reputable breeder. Guaranteed to be much healthier.

 

It’s usually not the result of your own aquarium but where you got the guppies. Assuming you got them from a petstore, theres your problem. If you’re serious about guppies you should buy them online from a reputable breeder. Guaranteed to be much healthier.

I did get them from a petstore but they were all healthy and had been in the tank for a week. None had any signs of disease or injury upon purchase and the male guppy had been active until the two days before he died where he stayed in one spot far away from the killifish who I had seen going after the older guppy. The fact that he ended up with an injury just behind his gill, the female that died had 0 fins left on her, and the old guppy had been losing his back fins (who has lived for over a year coming from the same petstore) tells me this isn’t a “petstore” guppy issue. Not to mention that since moving the remaining two guppy they’re also more active, eating well, and also have 0 injuries.

so yes, I blame the killifish, who—upon looking it up—is known to be a fin nipper (which was poor research on my part, I will admit). Am I serious about guppies? Not really. I wanted to put some guppies in and see what they make and how self-sustaining they could be before I’d have to separate the male. Do pet stores get garbage fish? Sure. But because of that and what I wanted to do I didn’t want to go to a guppy breeder. Not to mention the price of 2-3 guppies would be at least $40 when I could get pretty mutt guppies for $15. Not even looking to sell the babies either. I’ve got 4 tanks with room to hold them and am just enjoying them. Mutt guppies or otherwise

 

Nowadays, more so then ever before, ive noticed pet store guppies just will not survive. I buy them too from time to time, they are just waiting to be sold and then die in your tank. Most show signs of just total collapse. I blame the wholesaler, who keeps guppies in crowded wholesale tanks, and medicates them prophlatically i think. They are on to their 3rd diffrent water source by the time you take them home, and they loose their slimecoat and die from shimmies or a fungus infection. I use to buy petstore guppies all the time, and they were perfectly fine. A few years ago florida had some huge hurricanes, and wiped out most of the guppy stock. They had to start over. Ever since then the guppies coming up north have not survived in my aquarium while in the past they did great. In fact the yellow micairff in my picture were originally from a petstore. I just was making that statement because in my opinoin guppies from petstores have LATELY been that falls apart and dies for no reason. Hence, the damage has been done by the time you purchase them.
You cant see ammonia or nitrite poisioning, you cant see a damaged slimecoat, or internal parasites. Just coz they "look good" at the store dosent mean they havent been damaged during shipping or at wholesale warehouses.