A Guide (+ Chart) to Choosing Glofish Tank Mates

61 thoughts on “A Guide (+ Chart) to Choosing Glofish Tank Mates”

1. Thank you for all of the helpful info!
   I have a 20 gallon with 5 glofish danios, an Oto, and a few ghost shrimp. I’d like to add either 5 Glofish Tetras OR 4 Molly’s to the tank. Since both are schooling I worry that it might overcrowd my tank to add either breed. Do you think it would be possible to add without overcrowding??

   • Hey there,

     I think that adding 5 Glofish Tetras would be okay, as long as you have a decent filter and you stay on top of the weekly water changes. If there’s some aggression after, monitor who harasses who. You could add 2 more specimens to the aggressors’ school to mitigate the bullying, without worrying about overcrowding.

     By the way, is the tank a 20G Long or a 20G Tall? Long is better for schooling fish. I have an article on fish tank dimensions for reference.

     Also, some live plants would do the system well, for extra filtering and breaking the line of sight between fish.

     Hope this helps!

     – Momchil

     • Awesome- thank you that helps! Added two tetras and they’re doing great! It is a 20 long but kicking myself for not reading your article before purchasing the 20, I wish I had bought longer for the danios.
       Thank you for the helpful info- I’m a newbie to all of this. The tank was for my kids but it’s going so well that I just ordered myself one as well.

2. Hello Momchil, i have 4 tetras i just bought a 36 gallon tank so please tell me i want to add fish but i want your opinion first.What fish will work best and not kill the fish i have now?

3. Hey is it good to start off with one set of fish and then start adding the others.. And should I do the same amount for each set.

   • Hey hey,

     Yes, that’s how you’re supposed to do it.

4. So would it be okay for me to put Glofish danios with Glofish tetras?

   • Hi Samantha – yes, as long as the aquarium is big enough to accommodate at least 6 specimens of both. 🙂

     Good luck!

5. Yo maybe I can get some input from you; The Glow-Sharks I’ve heard they get to be only 4″&are good@ algae control, I’ve a 30 gallon long Aquarium that I’ve set up as a indonesian hill-stream bio type(it contains 4 pieces of driftwood w/ marine-land penguin 200 bio-wheel& betta bowl waterfall sponge filter to provide filtration however I have ended up dealing w/green hair algae, brown algae+ dark green algae growing on the glass& yellowish white hair algae growing on driftwood…from what I’ve seen given my setup there is chance I can manage to get 4 of the glow-sharks to co-exist with each other thus having a awesome team of algae eaters/scavengers.. any information from your knowledge on these fish would be helpful& yes I know I’ll be trying to attempt something that is considered 50% chance of working!(however I’ve been blessed by Immanuel to be able to pull off natural underwater ecosystems in the average aquarium)

   • Hi James,

     A single Gloshark requires at least 35 inches of vertical swimming space and at least 12 inches of aquarium width. I think stocking your 30-gallon with 4 of them would be off-limits as they will likely have territorial disputes and display aggression among each other.

     Also, Glosharks do eat algae, but I would not consider them a reliable algae eater. For a hillstream biotope, I would suggest looking into Chinese Hillstream Loaches as an algae-eating option.

     You could also try to eliminate the reason behind the algae (direct sunlight, excessive Phosphate or other organics in the water, etc.) I have an article on Black Beard Algae on the blog that you may be interested in (just use the search bar). It covers ways to deal with most hair algae growth in an aquarium.

     Hope this helps.

6. How big would the tank need to be in order to house a school of glofish tetras and a male betta? He is very peaceful for a male.

   • Hi,

     I would put a minimum of 7 and a maximum of 9 GloTetras and a single male Betta in a 29-gallon tank. Black Skirt Tetras may nip fins but in a school this large and a tank this big, I don’t think it would be the case. The larger the school the more they keep to themselves.

     I recommend monitoring their behavior in the first couple of days though. That’s always a good measure.

7. I am new to this whole fish tank thing. I am purchasing a 55 gal tank and would love some glofish tetras and angel fish. According to your chart, the two should go nicely as long as I have at least 5 glofish. What do you suggest as far as how many of each I should get and maybe the habitat as well? Totally entering into new territory

8. Should have added clear pictures for newbies. Otherwise an all around great article.

   • Hi, thank you!

     I will probably list them when I get some free time. Thank you for the feedback, Peaches 🙂

9. Hi! So I bought a ten gallon glofish kit, after reading this I realize I should have gone larger. In any event, I cycled the tank for a few days with bacteria and conditioner as directed by the pet store . When I returned to the store with my water sample I was given the “ok” to get four tetra glofish and 1 danio (also a mistake?) Three of the tetra glofish died in 24 hours. Do you attribute this to an amonia spike or possibly the danio attacking the tetras? Thanks!

   • Hi,

     First off, I’m glad that you’re brainstorming and doing research despite being new to the hobby. Keep it up.

     Secondly, I’d probably attribute this to an ammonia spike, because you added 4 fish at once in a space of 10 gallons. Bacteria were probably not ready for this and the addition should’ve been more gradual. Either way you’d probably still have some issues such as fin nipping if the tank was cycled.

     Just a quick question – what product did you use for cycling and how long it took? Did your fish store tell you the exact water parameters?

     Regards, and keep being eager to learn

     • Thank you for following up on my questions, it’s great to have someone knowledgeable helping us newbies.I added 10 ml Microbe Lift Xtreme conditioner every day for the first 3 days and Microbe lift beneficial bacteria as directed, on the fourth day I added the 4 glofish tetras and danio. I think your assessment of too many too early is correct. Do you think I should wait the full 4 weeks before restocking? Thanks in advance.

     • Thank you for following up, great to have someone knowledgeable helping us newbies. I added microbe lift xtreme 10 ml’s a day for 3 days, as well as the microbe lift beneficial bacteria once. On the fourth day I was told my sample was good. I agree with your assessment that I added too much too fast. Do you think I should wait a month to improve the bacteria before restocking? How many fish do you suppose I can keep in the 10 gallon? Eventually I would like five tetras, five danios, one or two other species like platies or guppies. What’s your take?

       • 4 days is way too soon to completely cycle a tank with any brand of bottled bacteria. Your desired setup is achievable, however, it does fall on the “overstocked” side of things so be prepared to introduce lots of live plants, a porous substrate (to have more bed for beneficial nitrifying bacteria) and a good water filter with plenty of space for biological media (same reason as with the substrate). I would not recommend having that many fish in a 10 gallon but with proper conditions it can be done. Also you should definitely wait at least 2 to 3 weeks before restocking, even with the use of bottled bacteria. I have an article on that called “api quick start vs tetra safe start” where you can read about my fish-in cycle method that I use on my aquairums.

         Hope this helps. Good luck, PJN

         • My rationale for wanting this many fish is due to their preference to school. Thanks for all the advice Momchil.

         • Update, not good. I added a porous substrate and allowed the three glofish tetras that to cycle the the tank for two weeks. I added four more glofish tetras, three of the new fish died the next morning another later in the day. My PH dropped to 6.0 and I added API up and did a 25% water change. I’m hypothesizing that adding four fish at once overwhelmed the tank. I’ve read that a significant drop in PH kills helpful bacteria, does this mean I have to start a brand new cycle? Would investing in a stronger filter help? Does the death of one fish really screw with water parameters and precipitate a bad reaction?

         • I would hypothesize the same. 4 fish at once is really too much for a 10-gallon aquarium. PH could have dropped exactly because of bacteria. Their nitrifying process does increase the water’s acidity, but that should be over time. Dropping to 6 at once is a little bit too extreme. The Nitrobacter do cease their activity around 6 pH, true. My other hypothesis is that your substrate lowered the PH. I have an article on substrates here and there you can see why this has happened and find out if it was the substrate’s fault. You’ll likely need to buffer the PH, by increasing the KH also known as carbonate hardness in the context of fishkeeping. Adding a little crushed coral will do the job of increasing the carbonate hardness. However, before doing so please make sure it’s not the new substrate’s fault (I’m pretty confident that it may be).

           Anyway, fish deaths do pollute the tank, yes. In your case, it could be the pH swing that killed them and not elevated ammonia. What were your water readings when you found out about the incident?

         • Thanks for your insight. To answer your questions I have been using standard glo gravel and had only been testing PH. However, today to help remedy the situation I invested in an aqua clear 20 gallon HOB to help filter ammonia and waste.Additionally, I bought alkaline powder and a master test kit to help
           attain better water parameters. Could changing the substrate make a big difference? I’ve vacuumed the bottom with some success but would adding a Cory help? Thanks again.

         • Hi

           AFAIK the Glo gravel should be inert, meaning that it should not alter the water’s parameters. Investing in a filter is a wise decision, but investing in a master test kit is an even wiser one. Test strips do not show reliable readings. pH is not a good benchmark to see if your fish tank has cycled. Test with the master test kit and see if there’s any ammonia or nitrite. That’s nitrite with an “I”. If even 0.5 ppm of either shows on the test, then your tank is still not cycled and you should wait with adding the fish. Adding a new cory would in fact generate too much waste at this moment. They are good cleaner fish but they do not suck up ammonia (if I understood you correctly, sorry if not).

           A cycled aquarium’s parameters are definitely 0 ammonia, definitely 0 nitrite and generally between 10 and 20 ppm of nitrate. When you see these readings (give it time) you can gradually add more fish. You can speed up the cycling process by adding bottled beneficial nitrifying bacteria.

           Hope I was of help.

         • Definitely helpful. I guessed that adding a Cory would clean the substrate and reduce leftover food and waste breakdown.

         • Yes, correct, it will do a good job at scavenging leftovers, however, these nutrients remain in the system and will eventually build up as a waste product and start degrading to ammonia again.

10. I have a goldfish and tetra fishes in the same tank there is now problems ever

    • That’s a typo it’s supposed to be no not now

    • It greatly depends on temperaments and the size of your tank. If you got lucky with a timid goldfish and a balanced school of tetras that inhabit a fairly large aquarium you can pull it off, but not every time in my experience. I try to minimize leaving things to chance with the info I provide to make sure my readers do the right thing.

      Thank you for your valuable input, Ritu.

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