Marine aquarium keeping is trending toward more "complete" representations of sections of natural marine environments; and there are good reasons for this change to biotopic set-ups. Fish-only systems are not only more work to keep clean, they're not nearly as beautiful as aquariums that include the living components of macro-algae and invertebrates.

Macro-algae (ones you can easily see with the naked eye) are of tremendous benefit to captive systems. They help optimize and stabilize water quality, compete with noisome types of algae for light and space, provide a ready source of food'¦ and they look great! There are several varieties available, broadly classified by their color or principal photosynthetic pigments.

Perennial favorite amongst the Green algae are species of the genus Caulerpa. As serpentine strands, tendrils, or beads anchored in the substrate, they are amongst the best marine algae for saltwater aquariums. You can buy these already anchored to a hard substrate or "free floating" and anchor it gingerly in your gravel where it will quickly spread by "runners".

Other great Greens are available this time of year in good numbers. Halimeda, Penicillus (Merman's Shaving Brush), & Udotea (Sea Fan) among them. All are good growers in well-established systems. They should all be placed with their bases just barely stuck into your substrate.

And your selection in macro-algae isn't limited to Greens. The Brown forked Dictyota, and Red Graciliaria are superb this time of year. The former requires a steady supply of iodine, so this should be supplemented quickly.

Some good news regarding these hardy non-plants: you may not have to buy them! Very often macro-algae "beginnings "come in" as part of healthy live rock. Rather than making a big effort, with adequate lighting, filtration and circulation you may have to actually prune your macro-algae back.

Invertebrates:

Many new and old favorites in the way of non-fish animal livestock are about this season. By and large they should be handled like fishes, with a good two weeks quarantine.

Sponges, phylum Porifera, especially the lavendar, blue to pink Haliclonas out of the Indo-Pacific and Fire Sponges are excellent this time of year. Take care to not lift sponges into the air as entrapped gases within their structures can be deadly.

Considering the Stinging-Celled Animals (phylum Cnidaria), where to start? Cultured and wild-collected True or Stony Corals (order Scleractinia) are available in good supply, in particular the Staghorns (family Acroporidae). The human-fragment/propagated varieties are great for beginners as they are by and large easier to acclimate to captive conditions.

Some of the Soft Corals (order Alcyonacea) have never been better; colored Toadstools (Sarcophyton) and the Pulsing Corals (family Xeniidae) especially. There are a few of the non-corals of the group (called corals anyway) that are also in good health and supply this year; Blue (Heliopora), Fire (Millepora), Pipe Organ (Tubipora). Lastly, in this phylum I'd like to mention the much improved initial health of quite a few species of Sea Fans (order Gorgonacea) both out of the tropical west Atlantic and Indo-Pacific. Collectors and shippers are finally learning how to carefully transport these animals. Do consider trying them if you have a well-establish full-blown reef set-up.

Of the molluscs, the Giant Clams (family Tridacnidae) the folks who produce cultured livestock have really gotten their act together. My favorite Croceas are available in good numbers in Purple, Gold and Turquoise mantled varieties. For folks with large systems good captive-bred Maximas can also be had in these color morphs.

Amongst the Crustaceans, I'm very happy to see a steady supply of the important Biological Cleaners of the genera Lysmata (the Pacific L. amboinensis, the Peppermint Shrimp of the Caribbean, L. wurdemanni, and Scarlet, L. debelius) and Boxer Shrimp, Stenopus hispidus'¦ In my opinion, every hobbyists whose tanks will allow such biological disease controls should make use of them.

What makes an aquarium complete? It's more than fishes and water. Having live macro-algae and invertebrates that are compatible, even better, from the same sorts of environment and geography make for a naturally beautiful and easier system to keep.