Hatchetfish Missing Black Coloration?

HI guys, I own 3 silver hatchetfish and I have a question....

There was one hatchetfish that had a distinct black coloration on his dorsal fin, and it was acting like he was the boss of the other 2 hatchetfish. It usually likes to harass the bigger hatchefish and swim beside it almost the whole day if it sees it anywhere in his sight.

However, this morning when I woke up to feed them, that hatchetfish with the black coloration no longer has the black dorsal fin.... it in fact turned transparent like the other hatchetfish and it looks rather scared (swimming in the lower section of the tank and hiding behind plants). I wonder what happened that made it change its fin color? And no, he/ she is healthy. Eats well, swims well, poops well, and has no signs of illness.

Can anyone tell me what's going on in here? Did he: she change into a less dominant fish?

Also, how can you know if a hatchetfish is carrying eggs? Because one of it looks really fat, unless it's from the food I fed.

 

My guess would be that it was an old ammonia burn that healed. Silver hatchets are silver - they don't have other colors that signify dominance or anything else. The behaviors you're seeing are probably coincidental. Though I might add that you should be looking for at least 3 more hatchets, preferably more if your tank allows, because they are schooling fish and need friends to be comfortable. The aggression you were seeing won't be a problem with a proper school. Unfortunately I don't know anything about their breeding habits so I can't help you there, but in general if the fish stays fat it's probably bloated - if it's carrying eggs it will drop them in short order and go back to normal size.

 

Thanks for answering my questions.

Unfortunately I lost 3 other hatchets do to failed heater which spiked the temperature at 32°C, I bought a new heater for them so it won't happen again. I'm thinking of buying 3 more hatchets but my brain keeps telling me not to because for the past year I have lost over 10 hatchets from either jumping out of the tank, white spot, and the temperature fail earlier. They are my favorite fish, but I need to save more money if I need to rebuy more hatchets, since I will be purchasing a 40G tank this coming June.

They'll need to hang on for that.

Also I came back home today and the hatchet got its black dorsal fin back........ and it's acting normal again swimming on the top and chasing the other hatchets. Weird but cute little things. <3

 

That is strange. Are you able to post a photo? I'd love to see that spot. What a weird thing.

Do you have a full lid? They'll keep committing suicide if you don't. Everything makes them jump. I set a pint glass down on the table next to my tank and a startled hatchet jumped out the back. They jump to catch food in the wild so it's normal to them. As for the white spot, you mean ich? Ich is easy to treat by upping your heat to 86f for two weeks and vacuuming the spores out with water changes. It's also pretty much unavoidable if you want to keep fish, so don't let it keep you from getting more hatchets. They need to be in a proper school to thrive.

How big is this tank, and what else lives in it?

 

Sorry for the bad pic, my hatchetfish "Tuna Belly", keeps swimming around. But the dorsal fin was black and then it turned into this color:

I'm not sure why, but it was so weird. Also, my tank doesn't come with a lid, I had peacock guppies before so didn't really bother with a lid. At the moment I placed a plastic board as a lid replacement. Of course this isn't perfect but I used plastic wrappers and taped up any holes that are visible at the top. I'm also aware that they are schooling fish, but as budget screams to me... 40G tank first (at the moment my tank is 4.4G which is pretty small I know). I've done a lot of reading but I was only curious about the dorsal fin color change. Can't seem to find any information about it since there are limited sources about hatchets.

 

The fish with color in the dorsal is a male, and that mark is an indication that he's ready to breed. The larger, fatter fish are females heavy with eggs, and that is "egging him on" (sorry, couldn't help myself). He will come alongside a female, press against her, and if she is ready, she will release eggs and he releases sperm at the same time. They are just general egg scatterers, not looking for plants to spawn in/on. Any fish living on the bottom of an aquarium with them will get a free caviar treat.

You really need that bigger tank, the one you have is far too small for these very active swimmers. That's why they were jumping, which is a natural act for Hatchets anyway; it's how they excape predators in the wild. They are as close as any Freshwater fish gets to a "Flying fish". It has been observed that they vibrate their large pectoral fins when in the air, possibly to try and prolong the flight.
A tight fitting lid will be an absolute necessity for keeping these fish, and when you have the 40 I would recommend a school of 8-10. A bigger school would be more natural, but would require a larger tank, of course.

 

Wow - I didn't realize the tank was so small. Have you thought about checking out Craigslist for a tank? You could upgrade a lot sooner by buying secondhand since it'd be so much cheaper, and you could most likely find a full setup for the price you'd pay for just the tank at a store. They really need to get out of that tank like, pretty much immediately....

 

Like I said, I will be purchasing a 40G tank this coming June. So at the moment I can't immediately go and buy one, because I am waiting for my paycheck. :/

Thanks for the information.... so that means I have 2 males and 1 unidentified gendered hatchetfish? Where did you get the sources from for their signs of breeding? And how big are hatchet eggs? chromedome52

 

Hatchets are also delicate fish. They congregate in warm surface water in the sunlight (silver camouflage). They need pristine water, and yeah, they can launch themselves 6 feet if they are startled.
They were my mother's favourite fish and I grew up watching three different species of them. The black dorsal is expected in G sternicla, the common silver hatchet.

It is hard to follow behind Chromedome's posts - the man knows his stuff. But he doesn't come on forum as much as a lot of us.

Breeding hatchets is a sign of skill - they aren't easy. If an aquarist tells me he/she has bred the fish, I am very impressed. I have never managed to see the eggs, though I have seen the behavior you asked about (the colour change).
The fish has been kept in aquariums since the 1940s, and experienced aquarists have developed quite a 'book' on them via discussion and sharing of experiences.

When you go tank hunting, consider finding a tank that can be high up. Hatchets are best watched from below, since they hug the surface. And get a good, tight cover! They will jump way less in a proper sized tank with a large surface area. They probably think they are trapped in a puddle and are launching themselves in the desperate hope of landing somewhere they can swim. We live and learn.

You've picked a wonderful favourite fsh, and now, as budget allows, you can get set up better for them.

 

Thanks for the information! I'm still learning about them and purchasing the right kind of tank size and plantations. It's very nice to watch them swim with each other, they are so adorable!!

I will keep those in mind of what you said, about buying more hatchets when I get my paycheck.

 

I never knew that about the dorsal fin, . Interesting!