The "wait, isn't that a freshwater fish" club.

[Tired]

I spent too long staring at the guppy tank at Petsmart.

Guppies can be acclimated to full saltwater, if given plenty of time, so I'm acclimating these over to live in my reef. First stop: slightly below the level normally used for hyposalinity treatments, so that, if any pathogens manage to get over from the true saltwater fish in the quarantine tank next door, said pathogens will die. Once the fish next door are done with prophylactic meds, I'll raise the guppies (slowly!) to full saltwater, probably by simply replacing evap with salty water, and then put their neighbors in with them for a little while so the main tank can finish up a fallow period. These are all males- I won't be adding any females. I want 5 guppies, not 500.

I haven't kept guppies in a long time, and I was too tired to appreciate them when I did. These guys are really cute, and my cat loves them, so I've wound up making an additional order; seven high-content Endler's livebearers. For those unfamiliar, endlers are a close relative of guppies, but are smaller, with an almost glassy-metallic coloration on the males. They're frequently hybridized with guppies in the hobby, both for looks and for size. The ones I've ordered all look to have a fairly low amount of guppy in them, so they should stay quite small as adults- 3/4" or so. If I could weigh them, sans water, in a stress-free manner, they'd probably add up to about a small shrimpgoby worth of bioload. I'm excited for these- I've never kept endlers, and I expect the lights to make them look really interesting, with their natural glossiness. Whether it'll be a /good/ sort of interesting, I don't actually know. We'll find out!

If I like how the endlers look, I may, once the original batch has died of old age (they generally only live ~3 years due to being tiny), pick up a batch of purebred endlers with some females included and get them breeding. I wouldn't do that now because I'd get guppy hybrids, which, though they're healthy and can look quite nice, aren't something I'd really be interested in an endless supply of. An endless supply of purebred endlers, though, I might like.

One benefit of these guys being freshwater: there's no quarantine period needed to rid them of disease. Acclimating them to saltwater will kill any pathogens they might have picked up. The corresponding downside is that they have no natural resistance to saltwater diseases, so they're vulnerable to anything their tankmates might bring in.

I'll update with some photos when I eventually have them in full salt and we can see how they look under the reef lights, in the reef environment. In the meantime: who else has freshwater fish in their reef? I know mollies are semi-popular, and surely someone else on here has, or had, guppies in their tank.

(as to the question of "why would you put freshwater fish in a reef": they're cute, I'm expecting them to look interesting at the very least, their small size means it's not much bio-load even with a decent few of them, and it's great cat TV to have them zipping around. Plus, honestly- I think it's funny to have probably the most recognizable freshwater fish in a reef tank.)

 

[Flatearth]

My LFS always has mollies in salt for sale. When next to actual marine fish you can really see the difference in their movement. The mollies look like cardboard cut-outs compared to the marine fish. They are just so stiff if that makes sense? It's not even that they look ugly, they just look like someone edited them into a video of a saltwater tank even in person. A con that probably also applies to guppies is they have no sense for marine danger. For example most fish know not to touch an anemone, but the mollies will swim right into it as if it is a plant according to my LFS.


As for the guppies maybe this is a crazy idea, but wouldn't they be good tank mates for seahorses? Guppies won't appreciate a lot of flow just like a seahorse, they have 0 marine illness on them guaranteed which is a big plus, they are not aggressive, and they are not fast eaters so they shouldn't out compete your seahorses. Unless I am really missing something they sound perfect for a seahorse tank.

 

[PlayerOne]

I find if I keep the nems fed...if my mollies swim into them...they will only sting them a little bit......after a week or so the mollies learn to steer clear of the RFA's....and not bite the torch tips.

 

[Tired]

Guppies definitely move differently than most saltwater fish, but it's in a wiggly sort of way that I like. That yellow one has little black marks on its pectoral fins that flutter nicely as it moves. Mollies do also move differently, I think maybe because they're usually from still water?

I'm solving the guppy/anemone problem by not putting any anemones in with the guppies. RFAs probably wouldn't be too bad, but there is a risk of a RFA curling quickly around one on reflex and stinging the poor thing up. I also don't have any torches, or anything else known for its sting- except a couple of acan echinatas, but I don't think they're fast enough to catch guppies.

They probably would make good seahorse tankmates. The only complication I can think of is that guppies nip at various surfaces in case there's food, and they might taste the seahorses. I don't think they would do any harm, mind you. I just don't know if they would annoy the seahorses over time, or if they would learn that a seahorse is not tasty.
Guppies are reasonably fast eaters, but also very easy to distract- a sprinkle of flake food on the surface would lure them away from potential theft during mealtime.
And, as a bonus, guppies don't mind the slightly cooler temps that seahorses like. They're temperate fish, you can keep them in unheated tanks.

 

[Tired]

Another bonus I've just realized for guppies in a seahorse tank: you get to confuse any visitors who know that guppies are freshwater and seahorses are saltwater, which is, I'm fairly sure, most people.

 

[Lbrdsoxfan]

Following. My importer acclimates the brackish mollies to full 1.026 salinity regularly. I'm curious on how the process goes.

 

[Tired]

Temporary, very high-tech acclimation setup. Only the best of vaguely dirty clay pots and two-piece jury-rigged lids. No heater, because guppies don't care. It took me a few days to get them to reliably eat any of the foods I have on hand, probably because I'm offering frozen and freeze-dried and they've only ever had flake, though they did go wild for some spare live BBS. They've now learned that the non-flakes are food as well.

I currently have five regular fancy guppies, and three endler/guppy hybrids. They were drip acclimated to a salinity of 1.008 over the course of a few hours, and seem to be doing fine; I haven't seen any signs of stress, beyond what's normal for small, active fish being moved to a new setup.

The endlers should be arriving next week. I don't want to drip acclimate shipped fish for hours, so my plan there is to float acclimate them (in closed bags) to a gallon or so of RO water, treated with minerals to raise it to the same pH they're shipping in. That gets them out of the ammonia bags and into a container with hiding spaces, and I can then slowly drip acclimate them to 1.008 and put them in with the guppies. I'll give them a week or so to make sure they're doing well in that, then start raising the salinity.

I have seen people reporting success with dumping mollies and/or guppies straight into full saltwater, but I can't think of any reason why acclimating more slowly would be a problem, assuming the fish are in good conditions (clean aquarium, decent food) the entire time.

These are the endlers I'm waiting on, all of which should have plenty of endler blood in 'em. I'm not familiar enough with endler strains to know by name which of these are intentional guppy hybrids (like the cobra endlers) and which are mostly endler with a little accidental guppy, but I'm willing to bet it'll be easy enough to guess once I have them in hand and can look at them up close. They're definitely not purebred- endlers aren't purebred unless they come with a pedigree. Even ones that look like purebred ones are about guaranteed to have some guppy mixed in.
(Not that it matters, since I won't be breeding them and hybrids are perfectly healthy. It's more for curiosity's sake. I'll be interested to see how they differ in behavior from the guppies, and I'm definitely interested to see how all those distinctly freshwater-fish colors look under reef lights.)

 

[c-horse]

Thanks @Tired for documenting your process. I have been thinking about doing the same thing, adding some guppies/endlers to my reef tank. I am hoping to use them to help eat the algae in my tank. I wonder if they would bother the zoas and gorgonians?

 

[Tired]

Well, guppies do nip at various surfaces, tasting for food. I would probably not put them with any of the really toxic palys, as I can't imagine a mouthful of toxic slime would be good for them, but their nipping is generally spread out enough and their mouths are small + weak enough that I don't think they'd hurt anything. Unless they decide something is tasty or interesting and really set to it.

I'll keep an eye on how these do with corals. They certainly aren't set up to eat corals, their nipping is to scrape up algae and biofilm.

 

[Tired]

Boy. They weren't kidding about "shocking pink".

That purple one definitely has a lot of guppy content in it. Handsome little thing, though, much prettier in person. The pink one and the cobra one look like they have less guppy but still a noticeable amount, and then the rest are mostly endler.

The tiger endler was DOA, but the other six seem to be doing well. They ate a little in the acclimation bucket. I transferred them into some clean freshwater to get them out of the bags, then acclimated them to the 1.008 salinity over the course of a few hours. They're in the tank with the rest, wiggling around as normal.

I have had a thought about acclimating them to full salinity. I've found some accounts of slow acclimation not going over well, and it's occurred to me that whatever function kicks in to let them transition between salinities might need to be triggered by a distinct shift in salinity, meaning a very slow transition may not allow it to kick in.
Therefore, instead of a slow and steady acclimation over the course of a week or so, I'm going to do it in multiple faster stages. I'll remove a few gallons of water from the tank, then drip new, saltier water in to raise the salinity a chunk of the way, over the course of a few hours. Maybe to 1.014 or so the first time, then 1.020, then 1.026? I'd give them a few days to rest between each acclimation, and to make sure they're doing all right. A compromise between the really slow acclimation and just dropping them in.

 

[Zionas]

Some people say Coral Beauties look too much like FW fish but I think they’re one of the simplest / most common but still elegant dwarf angels. Never been a fan of the aberrant varieties though. When did having a skin condition (though that’s probably not it) on fish become attractive? They sell for high prices but the vast majority revert to normal blue CB colors.

 

[Janet Belanger]

Following. My importer acclimates the brackish mollies to full 1.026 salinity regularly. I'm curious on how the process goes.

I literally tossed mine from petco into salt water and they lived for 18 months, and stared getting huge. It takes awhile for them to get strong enough to manage the current, and they were the best algae eaters I had.

 

[Tired]

One of the mostly-endlers seems to be having some trouble. It was actually sitting on the bottom when I first saw it, then went to lurk around a bit of cover, looking wobbly. Whatever combination of mechanisms lets them sit completely still and steady in the water doesn't seem to be working well for this one- it moves side to side as its pectoral fins beat. I gave it some food, and it ate a little, then went to slowly swimming around near the others.

I'm not sure what's up with it. The rest seem entirely fine, so I don't know if this one is handling the acclimation poorly, or if something else happened. My other thought is that it may have jumped and hurt itself on the lid, although I don't know if these little things can get enough momentum going to cause head trauma. Or maybe one of the bigger ones chased it for some reason and really freaked it out.

I'm leaving it alone for now. Trying to acclimate it back to freshwater would just put more stress on it, and I don't know for sure that the salinity is actually the problem.

 

[Leo_ian]

ive had pseudomugil signifer in a full saltwater tank for about 3 months and they even spawned. but aptasia ate them all up

 

[Tired]

Ah, yeah, those were another one I looked at to try in here. They're wonderful little fish, and I might try them at some point, but I wasn't keen on the price compared to their very short lifespan. I'd want to have them in a tank set up to encourage breeding and general multiplication.

The endler that was doing poorly yesterday seems fine now. I really do think maybe it hit its head on something and temporarily dazed itself.

 

[Leo_ian]

Ah, yeah, those were another one I looked at to try in here. They're wonderful little fish, and I might try them at some point, but I wasn't keen on the price compared to their very short lifespan. I'd want to have them in a tank set up to encourage breeding and general multiplication.

The endler that was doing poorly yesterday seems fine now. I really do think maybe it hit its head on something and temporarily dazed itself.

you could probably spawn a few in freshwater and move their babies into salt

 

[Tired]

That would require me to have an entirely separate tank, though, at which point I might just rather set up a nice planted tank for them.

 

[Leo_ian]

how about violet/dragon gobies, i know people say they're euryhaline but i've yet to see someone put them in a reef tank

 

[Pro2704]

bump

 

[Mhamilton0911]

although they can live in saltwater, I find guppies to be too fragile for the stronger flow we use in our reefs. I have acclimated guppies to salt, and yes they lived, for a while. the males perished first and the females lasted a little while longer but overall, they just don't hold up. Mollies on the other hand, are tougher and more robust so they fare better.

I certainly wouldn't put high end guppies in a regular reef. Maybe a micro algea tank or one with significantly less flow, but not the common reef setup.