"Suddenly" Aggressive Golden Zebra Loach...Help Please

[MariaBlue]

So, I've had this "guy" for almost a year - sweetest, funniest, active member of my 36 gallon fresh water community tank. He has never chased another fish (to my knowledge and it's in my office where I sit about 9 hours every day). About a month ago, I changed my substrate from gravel to Fulval's Stratum based on recommendations from a few places to help with my plants and make shrimp happy (future purchase). It seems as though since I made the substrate change, my golden zebra loach has gotten really aggressive with many of my other fish...chases my Cory, my platy, my molly, and my danios. I've had all of the fish in question for months and months and there have been no new fish added. He/She goes after them at every level of the tank. I believe it's killed two of my danios (one had a missing eye one morning and the other looked to have a "bit" one morning. Both died the same day I saw what appeared to be wounds and I'm now suspicion that he stressed my ). Anybody have any advice? Anything I can do to make it happy again? I really like it, but like my other fish too! Thank you for any insight you can lend.

[Bas Pels]

What I think is going on is that the loach really, really disliked the gravel you had. It disliked it so much that is went into what we would call a depression in a human. It could also be that the gravel hurt it and being hurt it went inactive

Now the gravel is gone, the natural behaviour returns. Loaches ought to be kept in a group, preferably 6 or more, and is not, some can get overly agressive. Remember, living in a group is intended to be a protection. Failing such, the fish, any fish, can react by getting more carefull, that is hiding more, or getting agressive - doing it to them before they are doing it to you.

On a first sidenote, I wonder whether loaches and shrimp is a good combination. Loaches might eat them

my second sidenote is that a group of loaches can be rather intimidating. I have Rasbora borapetensis combined with Schistura bachmaensis, 8 of both, and this cvombinaton does not work, the Rasboras are very shy, sitting in the darkest place of the tank, doing nothing, while they ought to be active quite close to the surface. I think the Schistura, which are very active during feeding are to blame, and I will remove the Rasboras. Soon

[MariaBlue]

Hmmmm, I think I follow your thought process. The one contrary thing is that it was never not active - it was always swimming around (in fact, the silly thing used to go around and around and around the suction cup connection between the aquarium back and the intake wand...like a ferris wheel chasing it's tail!!!). I do feel as though somehow it must be connected to the substrate change...and I'm frustrated by my local fish person because she recommended the single golden zebra to help with a snail infestation and ASSURED me that it would not eat my shrimp!!!! I have lost shrimp, but I usually find them in the canister filter, so figured they were getting sucked in (I've purchased a mesh cover to protect from that), but now you're making me question the shrimp with the loach at all. Grrrr. I'm wondering if my local fish place will take it and resell; I'll have to check. I love him, but really hate to see it chasing and stressing my other fish

[redshark1]

This problem could be a result of keeping this species (which I know as Yoyo Loach) differently to the care recommended.

According to this website, which I feel is authoritative:

https://www.seriouslyfish.com/species/botia-almorhae/

"As always, thorough research prior to selecting a community of fishes is the best way to avoid problems.

Botia spp. are gregarious, form complex social hierarchies and should be maintained in groups of at least 5 or 6 specimens, preferably 10 or more.

When kept singly they can become withdrawn or aggressive towards similarly-shaped fishes, and if only a pair or trio are purchased the dominant individual may stress the other(s) to the extent that they stop feeding."

There is also a guide here on Loaches Online.

[NancyD]

To me "golden zebra loaches" are botia histrionica, not yoyos (b. almorae). No matter, I think Bas Pels has it right. It's lonely & aggressive because of that. It wants same species "friends" & will try to get other fish to fill that need & acts aggressive when they don'y respond in the right "loachy" way. Kept in too small groups some loaches are like that, 1 is "alpha" without enough others of its same kind to spread out any aggro. But a lone loach of a schooling/shoaling species (many of them!) that behavior can be amplified. None of the other fish know or do what the loner expects...

I think I would rehome the loach unless you can offer more (5-6) of the same species...& you tank is pretty small for all those loaches...You didn't know, there's no need to feel guilty about it but fix it soon.

[Bas Pels]

To me "golden zebra loaches" are botia histrionica, not yoyos (b. almorae).

That's the problem with common names such as "golden zebra loach". What could this be?

I am Dutch, not a native speaker of English, and I have not a clue what species is involved. On one hand this does nopt matter indeed, as the mentioned problem is common for (almost) all loaches. But on the other hand, even in small areas common names can differ. Thayeri boekley has some 10 common names in the Netherlands, a country with 17 miljon people in it, and an area as big as Maryland in the USA.

Imagine the number of names in the English speaking world. It is so much better to use the latin names.

Loaches are not very common in fish keeping. That could even result in fish store owners invening their own names, and these names could be reused for later shipments, with other species involved.

[NancyD]

Yes, I don't like common names either, Bas. When I searched "golden zebra loach", another loach genus came up, a sinibotia. There are zebra loaches, (b.striata) too. Clown loaches most of us know, but also royal clowns (a leptobotia species), not related or common...

Especially in an international forum we should all try to use latin names in addition to "common" names when possible although some are easier than others. "Sids", "yoyos" & pangios (often just called "kuhli" loaches for any of the genus) are fairly easy to understand but "hillstream" is a habitat, not any genus or species, there are many.

It's hard for new people to go beyond what the shop may call a fish & lfs may have gotten a mixed species grouping as a single "common" name. This especially difficult if the fish are young & small. I've seen this more & more often the last few years.