In Your Experience, What Have Been Some of the Most Problematic Fish?

[duanes]

To me Leporinus is one of the"the" most misunderstood species, and its not the fault of the fish, but the aquarists, and the misleading available info.
This is not a normal community tank fish., no matter what the care sheets tell you
To hold down aggression, they need to be kept in a shoal of at least 6 or 8, so trying to keep them as a pair or trio, is usually useless.'
And keeping them in tanks of under 6ft is another bad move, I've seen them recommended for 75 or 90 gal tanks, to me this is delerium.
They also come from fast flowing water in rheophillic currents which helps dissipate aggression, so a tank with only HOB or canister filtration is totally inadequate.
A 6 ft tank with a shoal of at least 8 with Couple high velocity power heads or wave makers would be a minimal way to house them to me.

But this is the only way I'd keep cichlids like Geophagus, as they are from similar habitats, and also shoal.

 

[jjohnwm]

Problematic fish? Interesting question.

I have never really had problems just keeping fish alive and healthy, but then again I have never been drawn to the challenge of keeping fish simply because they are known or thought to be difficult. I keep fish that I like; if they happen to be common as stink, and/or extremely easy to maintain, then I just lean back and enjoy it.

If I find a fish to be problematic, well, there's usually another fish in the next tank who will deal with the problem quite handily.

Problems for me tend to be centered around fish that breed too prolifically, forcing me to break out the blender and start mixing up another batch of Fish Jello. This is pretty much limited to livebearers, cichlids and, lately at least, goldfish. I don't enjoy this task, but it's a necessary evil.

My Electric Cat, way back in the day, gave me such a jolt once when I was being a little careless in his tank that I reflexively yanked my arm out and put my elbow through a plate glass tank cover leaning nearby. Still have an ugly scar on my upper arm as a reminder. Problematic?

I never got a serious shock from an Electric Eel that I had for some time, but honestly, I was so dang paranoid dealing with that thing that I am certain my blood pressure was way too high for those several years. Problematic?

I've never had any interest in Piranhas, but while working at a LFS while in high school, I again got careless and had my hand in the water at the wrong time when something spooked the whole school of them; I got a slice on my finger that was deep but so clean and fast that I didn't even feel it, just saw blood in the water. Don't like Piranhas, never wanted any...still get bit. Problematic, yes...my carelessness, though, not the fish's fault.

I think if I had to choose one species, it would be native Grass Pickerel, Esox americanus. I thought...and still think...that they were one of the coolest natives I could catch, and I collected them locally on a number of occasions. I simply could not get them to coexist with one another; the best outcome would be that they ate each other until I had only one left. Quite often I had none left, as both eater and eatee would end up dead, and on at east one memorable occasion, three last survivors in a tank...all very close in size...had seemed to sign a truce and were living well together...or so I thought...for months. Then one day they suddenly ended up as a sort of nesting-dolls arrangement, with one inside another inside the third, all quite dead. Larger tanks, more plants, more hardscape, different lighting...nothing seemed to matter. They were cannibalistic lunatics..."I'm gonna eat you"; "No, I'm gonna eat you!"; "Oh, yeah? Well, I'm gonna eat both of you!!!" I can't imagine how the species breeds successfully. I shudder to think how many of those fish I caught, brought home, and lost over a period of several years before I finally admitted defeat and gave up on them. I kept the last one alone for several more years before losing it to unknown causes, and never collected more after that.

So I suppose that fish is my Waterloo.

 

[CrunchyLobster123]

For me it’s always been guppies, not sure why but they never do well and tend to just wither away and die no matter what source I get them from my platies and sword tails always did amazing but guppies never made it long term. At one point I was doing something right and got a few generations going by adding a bit of salt and other buffers to the water but the colony ended up crashing about a year down the line which is so odd as my water out of the tap has a decent hardness and pH of 7.5.
My second most problematic fish are Red tail black sharks which are absolutely gorgeous fish and I’ve tried them a couple (3) times now but they always get so so aggressive to their tank mates my last one would even fight and bully Oscar’s. I’ve always been like “oh this one won’t be as bad as the last” and every time they turn out the same, I’ve tried keeping them with everything from large Oscar’s to small tiger barbs and they just attack everything I’d like to own one one day but as a species only “wet pet” kind of thing so I don’t have to worry about it attacking and bullying tank mates.

 

[CrunchyLobster123]

This may sound weird but African butterfly fish, I just could never keep them alive long term. I’m thinking they’re aggressive amongst themselves when I wasn’t around? And quite possibly over crowding played a part.

They definitely can be especially the males, I had kept a trio of 2 males and 1 female in a 75 and they lasted about 3 weeks until one male killed the other, but I’ve had luck housing 2 males in a 125. Imo they’re best kept solitary or as a duo in a 4-6ft long tank with lots of different surface structure (wood and plants) although they don’t move much they're definitely territorial and like their own space.

 

[Sassafras]

For me it’s always been guppies, not sure why but they never do well and tend to just wither away and die no matter what source I get them from.....My second most problematic fish are Red tail black sharks which are absolutely gorgeous fish.....but they always get so so aggressive to their tank mates

Ditto on the guppies, at least in the last 20 years. I've been in the hobby for over 50 years and all I can say, guppies ain't what they used to be. About as fancy as it got back in the 1960's-1970's were Red Tuxedo and Snakeskin varieties, they were big and tough. The number of strains and colors available now is amazing but, somewhere in all the breeding to create them, it seems like the guppy's hardiness and suitability as a "beginner's fish" was lost.

An interesting note on Red-Tail Sharks. I currently have a 230 gallon tank and among its inhabitants are 30 RTS! Always a few split fins, but the aggression gets spread out across the group that no major damage is ever done. And, the RTS are so preoccupied with each other that there is no aggression towards any of the other inhabitants, which include Congo Tetras, Pearl Danios, Angelica Botia, Red-Tail Banded Loaches, African Glass Catfish, Black Lancer Cats and African Butterfly Fish (2).